Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session KP1: Poster Session (3:204:05pm) 
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Room: Georgia World Congress Center Level 1, Exhibit Hall B2 by the GFM videos 

KP1.00001: STUDENT POSTER COMPETITION: COMPUTATIONAL


KP1.00002: Understanding Collective Function of Platelets During Blood Clot Retraction Yueyi Sun, David Myers, Wilbur Lam, Alexander Alexeev Blood clots formed during the wound healing process essential for restoring normal blood circulation. Disorders associated with blood clotting can lead to highly dangerous conditions resulting in bleeding, stroke or heart attack. Furthermore, undesired blood clots can lead to thrombosis diseases. It is therefore important to understand the physics governing blood clotting for developing efficient treatment of these disorders. During clot retraction, microscopic platelets extend filopodia to surrounding fibrin filaments to contract the fibrin mesh resulting in macroscale volume changes of the clot. We construct an experimentally informed mesoscopic computational model to examine the micromechanics of clot retraction. The model allows us to probe the effects of filipodia properties and platelet heterogeneity on fibrin clot dynamics. Results indicate that platelet heterogeneity associated with differences in platelet activation times is essential for achieving efficient clot retraction. 

KP1.00003: A Geometrical Characteristic of a Vortex Birth in Terms of Local Flow Geometry in Isotropic Homogeneous Turbulence Daiki Aoyama, Katsuyuki Nakayama The present study investigates geometrical characteristics of a vortex birth, i.e., brannew vortex in terms of the local flow geometry in an isotropic homogeneous decaying turbulence in the Direct Numerical Simulation. We capture the transition of the geometry in the vortex birth excluding vortex generation derived from transfer of a vortical region. We analyse with several physical quantities associated with the invariant and detail local geometry (Nakayama, FDR 2014). The swirlity that specifies the unidirectionality and intensity of the azimuthal flow monitors the flow transition where the swirlity changes from a negative to positive value. The quantity of the vortical flow symmetry shows that a vortex is born with much skewed swirling motion. On the other hand, the sourcity associated with the symmetry and intensity of the radial flow indicates that a born vortex has a tendency to have symmetric radial flow such as complete inflow or outflow in all directions in the swirl plane, because the intensity of radial flow is still dominant in the vortex birth. An inflow vortex has a feature to develop stronger that an outflow vortex. 

KP1.00004: Invariant characteristics of the eigenvorticalaxis line to pierce intense vortical region in multiscale flows in an isotropic homogeneous turbulence Hayato Hori, Katsuyuki Nakayama The present study investigates a feature of the eigenvorticalaxis line in terms of passing through intense vortical region in several decomposed flow scales in an isotropic homogeneous decaying turbulence in a low Reynolds number Re_{λ }≈ 35. This axis line based on the invariant local flow topology has stronger characteristics to pierce intense vortical regions in terms of the swirlity or vorticity, and to be normal to the maximum plane of the swirlity than the vorticity line. It is noted that swirlity represents the unidirectionality and intensity of azimuthal flow in the geometrical mean. The maximum plane is specified by the Hessian of the swirlity. We decompose a turbulent flow using the Fourier bandpass filter, and investigate these characteristics in decomposed scale flows. The analyses in decomposed multiscale flows show that the eigenvorticalaxis line has invariant characteristics to pierce intense vortical region and have stronger feature to be normal to the maximum plane of the swirlity than the vorticity line, irrespective of the flow scale. 

KP1.00005: Surfzone Setup and Alongshore Currents During Hurricane Matthew Jinshi Chen, Britt Raubenheimer, Steve Elgar The effect of winds on the setup (the increase of the mean water level owing to breaking waves in shallow water close to the beach) and on the alongshore surfzone flows during the passage of Hurricane Matthew (Oct 9, 2016) is investigated with observations and one dimensional numerical models (neglecting alongshore variability). Waves, mean flows, winds, and water levels were measured for 7 days between the beach and 11m water depth at the USACE Field Research Facility near Duck, NC. Bathymetry was measured before and after the storm. During the peak of the storm, wave heights in 17m water depth reached 5 m, setup was O(1 m), and alongshore flows (O(1 m/s)) reversed direction as the storm passed. Including wind in the models reduces modeled setup and alongshore flow errors up to 10% and 25%, respectively. The setup model is most accurate during the storm, and underpredicts the observations before and after the storm. The flow model underpredicts the velocities, but predicts the timing of flow reversal accurately. Using a wave transformation model and Snell’s law initialized with observations in 11 m depth to drive the models, rather than using the waves observed across the region, does not improve the results significantly. 

KP1.00006: Relationships between vortex stretching and its elongating feature among several scale vortices in an isotropic homogeneous turbulence Keisuke Yamamoto, Katsuyuki Nakayama The present study investigates the detail effect of the vortex stretching in terms of the interaction of vortices in the different flow scales in an isotropic homogeneous turbulence in low Reynolds number. The formulation of the vortex stretching associated with the swirl plane specifies its effect in detail, and completeinflow vortices has been shown to have effective stretching that increases vorticity for swirling and decreases inclination of a vortical axis in this turbulence [K. Nakayama, Phys. Rev. Fluids (2017)]. We apply this formulation in the analysis and show that the vortex stretching in completeinflow vortex has more intense interactional effect where the parallel stretching component to the swirl plane of a vortex in a scale strengthens the vorticity for swirling of a smaller scale vortex than that of averageinflow vortex. However, the vortex stretching in the outflow vortices in a scale weakens not only the vorticity for swirling themselves but also vorticity for swirling in a smaller scale vortex. 

KP1.00007: RayleighBénard Turbulence: Optimal Patterns and Dynamical Modes Andrew Corbato, Jiujiu Lou, Pedram Hassanzadeh RayleighBénard convection (RBC) is a fitting prototype for various engineering systems and natural flows. Focusing on a 2D RBC model with noslip walls, we follow the walltowall optimal transport framework of Hassanzadeh, P., Chini, G. and Doering, C., Journal of Fluid Mechanics, 751, pp. 627662, 2014 and seek divergencefree velocity fields that maximize vertical heat transport. We study a wide range of Rayleigh (Ra) numbers, Ra = 10^{3}10^{10}, to quantify the contribution of different components of the optimizing flow fields to the total heat transfer and extrapolate the results to the ultimate (i.e., asymptotically high Ra) RBC regime. We then focus on a long Direct Numerical Simulations (DNS) dataset of 3D RBC at Ra = 10^{6} and compute the Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) modes. In exploring both systems, we seek insights into the nature of the RBC turbulence and potential connections between the optimal patterns obtained from the 2D walltowall framework and the modes of the 3D flow. 

KP1.00008: Investigation of an Industrial Ejector Pump Design for the Assisted Bidirectional Glenn Using Multiscale Simulations Matthew Peroni, Mahdi Esmaily Moghadam The high mortality rate of neonates with single ventricle physiology remains unsatisfactory despite recent advancements in surgical techniques. A recently proposed alternative to the conventional stageone operation, called the assisted bidirectional Glenn (ABG), has demonstrated marked improvements in pulmonary flow and oxygen delivery while reducing the heart load. Alongside these favorable outcomes, ABG also leads to increased superior vena cava (SVC) pressure to a level that may not be tolerated by infants. This increased pressure was a result of an inadequate performance of the ejector pump that was embedded in the original design of the ABG. Thus, the objective of this study is to find an alternative design for this ejector pump that improves the mechanical efficiency and lowers SVC pressure. For this purpose, a representative threedimensional model of an ejector pump is created based on an industrial ejector pump design and its performance is simulated as a function of nozzle diameter, diffuser angle, and mixer geometry using a finite element flow solver. The performance of the final optimized geometry is examined in a more realistic model of the patient physiology using a multiscale 3D0D coupled simulation. 

KP1.00009: Computational Fluid Dynamics Study of Tumble Generation in Sparkignited Internal Combustion Engines Michael Colella, Paul Puzinauskas, Alex Voris An intake port development methodology was developed for a 2.4liter Chrysler Cirrus engine using computational fluid dynamics (CFD) simulations. A steadystate validation of the CFD computational accuracy was performed experimentally using a particle image velocimetry (PIV) test setup. The obtained experimental velocity fields were compared both qualitatively and quantitatively to 3 hypothesized turbulence models: standard kepsilon (SKE), realizable kepsilon (RKE), and komega (KO). Results indicated that the SKE model provided the most accurate simulation of the experimentally obtained velocity fields and derived nondimensional tumble numbers (NTN), with results all lying within a 95% confidence interval of accuracy. Compared to the mean experimental results, SKE proved to have a maximum percent difference of 4% and a minimum percent difference of 1%. Additionally, a transient simulation of the intake process was performed to predict how the generated vortices evolve as in a physical engine. Results obtained at bottom dead center of the transient simulation were determined to be extremely similar to the steadystate simulation results at the corresponding maximum valve lifts. 

KP1.00010: Structural Changes due to VaryingPhase Opposition Control in Turbulent Channel Flow Simon S Toedtli, Christine H Yu, Beverley J McKeon 
(Author Not Attending)

KP1.00011: Abstract Withdrawn 
(Author Not Attending)

KP1.00012: Abstract Withdrawn Within the field of magnetohydrodynamic (MHD) turbulence, a number of energy spectra have been observed that are not captured by the classical Kolmogorov picture of hydrodynamic turbulence, begging an advanced description of the energy cascade in MHD turbulence. In this work, the KármanHowarthMonin (KHM) equation is extended to flows with MHD forcing. Equations are derived describing both the evolution of turbulent kinetic and magnetic scale energies. The derivation is generalized to flows with variable density, viscosity, and conductivity, allowing examination of multifluid mixing systems. Terms arise in these equations describing both the transfer of energy between scales in the kinetic and magnetic fluctuations and the conversion of energy between these two types of turbulent fluctuations. The derived equations are used to examine both the transfer and conversion of kinetic and magnetic scale energy in forced MHD turbulence using a direct numerical simulation dataset. 

KP1.00013: Flow Field of a Point Vortex Inside an Elliptical Boundary Aidan Schumann, Rachel Pepper Twodimensional point vortices in Euler fluids are a common tool to model airfoils and geophysical flows. For instance, ocean vortices can interact with coastlines and other geometries that affect their motion. Such interactions have been studied around circular islands and in bays. While the flow external to an elliptical island is known and has applications to airfoil theory, the corresponding flow inside an elliptical boundary has not been studied. Here, we show an analytic solution for the flow field due to an ideal twodimensional point vortex in an elliptical boundary, as well as the motion of the vortex. We use conformal mapping to find an image system that satisfies the boundary conditions of no normal flow through the ellipse walls. This results in flow fields similar to those within a circular boundary but with the streamlines stretched to fill the ellipse. Similar to the circular case, the point vortex traces out concentric ellipses as it moves around the model bay. 

KP1.00014: STUDENT POSTER COMPETITION: EXPERIMENTAL


KP1.00015: Flow Calculations of Forced Buoyant Plume using Infrared GasVisualization Daniel Brun, Sudheer Reddy Bhimireddy, Kiran Bhaganagar The development of a forced turbulent axisymmetric buoyant plume inside still air environment is studied experimentally. Heated Carbon Dioxide (CO_{2}) is chosen as the tracer gas and is released into a gas chamber under controlled conditions. A FLIR VUE Pro thermal camera is used to record the development of forced plume. Scalar temperature field inside the plume is estimated using the intensity of the image pixels recorded by the thermal camera. Both instantaneous and timeaveraged fields of temperature are obtained from the recordings. Subsequent frames from the recordings are used to estimate the velocity field inside the plume and is compared against the analytical solutions for forced plumes. Preliminary analysis of mixing inside the plume is addressed by tracking the individual image pixels and their intensity changes in time. 

KP1.00016: Transport of interstitial fluid in the brain Ketaki Joshi, David Schaffer, Paul Chiarot, Peter Huang Accumulation of betaamyloid protein in the vasculature of the brain is a characteristic of Alzheimer’s disease. One potential mechanism to clear betaamyloid from the brain is via flow through perivascular spaces. Animal studies have shown that betaamyloid carrying interstitial fluid is transported out of the brain through the perivascular space along artery walls. There is evidence that the direction of this flow is opposite to that of blood flow through the artery lumen. The perivascular space is mostly made up of layers of smooth muscles and it is assumed that the transport is driven by deformations of the artery wall. The origin of these deformations may be from heart pulsations or muscle cell contractions. We report on a hydrodynamic mechanism for reverse flow through the artery wall consisting of forwardpropagating waves and their reflections. We have modeled the transport and identified a set of parameters to achieve a reverse flow. Measurements of arteries in the brains of anesthetized mice has been provided by Cornell University (N. Nishimura) using twophoton microscopy. Artery wall deformations from these measurements are used in our numerical simulations to predict interstitial fluid transport. 

KP1.00017: Surface swimming using highfrequency, lowamplitude motions Yuxin Liu, William Gorman, Christopher Muir, Jessica Shang An experimental investigation is conducted to study the thrust generated by a flexible flat plate at the airwater interface. The flat plate is driven by a voice coil actuator, which heaves the leading edge at a prescribed frequency and amplitude. In particular, the kinematic regime of interest is high frequency (10100 Hz) and low amplitude (4 mm or less). These motions generate surface waves in addition to bulk flow beneath the surface, which together produce thrust. The thrust and mean flow field will be measured by using a load cell and particle image velocimetry, respectively. Highspeed imaging will be used to visualize wave patterns on the surface and bending dynamics of the flat plate. Results will contribute to understanding the role that flexibility and wave production can play in surface swimming. 

KP1.00018: Determining the Effect of Raindrops Impact Location on Seed Dispersal Of SplashCup Plants Isabel Mejia Natividad, Rachel Pepper Splashcup plants are unique plants that use the conical shape of their seed capsules and the kinetic energy of raindrops to disperse their seeds. When raindrops fall into the mmscale cupshaped capsules the seeds are propelled out of the cup over 1 meter away from the parent plant, a distance up to ten times the height of the plant. The dispersal of these seeds maybe important to minimize the competition between the seedlings and the parent plant. Amador et al. used 3D printed models to show that a cup angle of 40° and offcenter drop impacts maximizes dispersal when no seeds are present in the cup. Although these findings indicated broadly that offcenter raindrops were more effective, no systematic study has been conducted to examine how the precise impact location on the splashcup plants affects seed dispersal. In this study, we used 3D printed splashcups and highspeed video to analyze the effect on dispersal of six different drop impact locations ranging from the center to the edge of the cup. We find results for different cup angles as well as in the presence and absence of seeds. We found that drop impact locations near the outer edge of the splashcup yield the highest dispersal distances in some cases. 

KP1.00019: Wind Tunnel Experiments on VortexInduced Vibration of a High MassRatio Flexible Circular Cylinder Nathaniel Anderson, Banafsheh SeyedAghazadeh Vortexinduced vibration (VIV) of a fully submerged, highlyflexible circular cylinder placed horizontally in the testsection of a subsonic wind tunnel is studied experimentally. The cylinder is tensiondominated with an aspect ratio of 47 and a high mass ratio of 120. Two synchronized high speed cameras recorded the oscillations of the cylinder in the crossflow and inline direction for a reduced velocity range of U*=3.663, corresponding to a Reynolds number range of Re=1871530. Continuous response of the cylinder is reconstructed from limited number of measurement points based on modal expansion theorem modified using Modal Assurance Criterion. Previous studies on VIV of flexible cylinder are carried out either on low mass ratio cylinders in water tunnel or low aspect ratio cylinders with high mass ratio in wind tunnel. Owing to the highflexibility of the cylinder used in the current experiment, mono and multifrequency responses as well as transition from low mode numbers to high mode numbers for a high mass ratio and high aspect ratio flexible cylinder are observed. The dynamic response of the cylinder is also compared to those of a low mass ratio flexible cylinder in the similar Reynolds number range tested. 

KP1.00020: Margination of plateletsized particles in normal and hardened red blood cell suspension flows Nozomi Takinouchi, Tenki Onozawa, Junji Seki, Tomoaki Itano, Masako SugiharaSeki It has been known that platelets in microvessels have enhanced concentrations near the vessel wall (nearwall excess, NWE). Existing studies showed that this phenomenon does not occur in the absence of red blood cells (RBCs), which indicates the essential role of RBCs in NWE. In the present study, we examined the effect of RBC deformability on NWE, by adopting plateletsized fluorescent particles for platelet substitutes to measure the crosssectional distributions of particles mixed in normal or hardened RBC suspensions flowing through microchannels. The fluorescence observation was performed over the cross section of circular or rectangular channels with use of a confocal laser scanning microscope system. It was found that in rectangular channels, plateletsized particles mixed in normal RBC suspensions were concentrated near four corners in the cross section, while in circular channels they were concentrated along the circumference of the channel wall. For particles mixed in highly hardened RBC suspensions, NWE was scarcely observed in both channels. These results suggest that NWE of platelets can be attributed to high deformability of RBCs, which induces their axial accumulation. The interaction with such RBCs expels platelets into the marginal layer near the channel wall.


KP1.00021: Internal Wave Kinetic Energy: Particle Imaging Velocimetry vs Synthetic Schlieren Kyle Hakes, Annie Wesolek, Heather Erickson, Allison Lee, Julie Crockett Internal waves generated throughout the ocean significantly impact the ocean energy budget. Historically, Particle Image Velocimetry (PIV) has been an extensively used experimental method for analyzing internal waves and propagating wave power. Synthetic Schlieren (SS) methods have mostly been used only to estimate the change in natural frequency (N). If SS methods can be used in place of PIV methods for internal wave energy analysis, the cost will decrease and the ease of computing will increase. The kinetic energy values of internal waves generated by an excitation frequency (ω) were computed using SS, using the models outlined by Lee and Crockett, and Wunsch and Brandt, for evanescent (N < ω) and propagating (N > ω) waves respectively. The results from the SS methods compared well with the results obtained from PIV. The experiments performed were focused on the kinetic energy generated from varying topographies and local density stratification profiles. 

KP1.00022: Sea lion’s use their foreflippers as a static wing while maneuvering Aditya A Kulkarni, Frank E Fish, Megan C Leftwich California sea lions are one of most maneuverable mammals in water, with observed turning rates of 690°/sec and low turning radii at high speeds. Unlike most biological swimmers that use a body/caudal fin (BCF) type of locomotion, sea lions produce thrust by adducting their foreflippers into their body, which is followed by a long glide in a streamlined position. However, here we demonstrate another function for the foreflipper which involves the sea lion using it as a lift producing static wing that helps generate the necessary torque for agile maneuvers. Cross sections of the flipper model resemble the shape of the airfoils typically found in wings with thickness ratios, 11%  37%. Wind tunnel testing on a laser scanned 3D printed foreflipper revealed that it produces lift over a wide range of angle of attacks, including negative angles. To complement the aerodynamic testing, surface oil flow visualization and near surface particle image velocimetry were conducted on the flipper. Results showed a complex threedimensional flow structure over the flipper with areas of heavy crossflow. 

KP1.00023: MicroActuators for Kinematic Optimization (MAKO): Manufacturing Shark Skin Inspired Surfaces for Separation Control Sean Patrick Devey, Amy W Lang, James Paul Hubner, Jackson A Morris Perhaps the biggest challenge facing any new flow control technology is designing a practical system. Shortfin mako shark skin has a passive dynamic microgeometry which serves to impede reversing flow and add momentum to the boundary layer. These effects result in augmented resistance to flow separation as demonstrated in water tunnel experiments. Engineering such a surface could be useful for aerodynamic applications. Additive manufacturing has been employed to manufacture surfaces that can capture the miniscule size, detailed structure, and passive actuation ability of mako skin. Several prototypes have been developed and tested. Wind tunnel tests of early prototypes have demonstrated scale actuation by flow in the lower 5% of the boundary layer. Revised prototypes are in development, addressing issues in the manufacturing tolerances of previous designs. A novel concept utilizing a flexible silicone base is also proposed and investigated. 

KP1.00024: Inertial focusing phenomena of neutrally buoyant particles suspended dilutely in square duct flows Hiroshi Yamashita, Ryusei Soen, Naoto Yokoyama, Tomoaki Itano, Masako SugiharaSeki Neutrally buoyant spherical particles suspended in laminar rectangular duct flows are known to cross streamlines, focusing on certain points at downstream cross sections. For square duct flows, recent experimental and numerical studies showed that there are several focusing patterns of particles over the duct cross section, depending on the Reynolds number (Re) and the particletoductsize ratio. In the case of the size ratio around 0.1, four focusing points, called channel face equilibrium positions (CFE), appear near the center of duct walls at low Re. This pattern is named “CFE pattern”, tentatively. At higher Re, new focusing points, called channel corner equilibrium positions (CCE), appear on the diagonal near duct corners, together with the CFE (CFECCE pattern). For larger size ratios (>0.3) at low Re, on the other hand, the appearance of CCE instead of CFE was predicted by a recent numerical study (CCE pattern). In the present study, we have aimed to elucidate the focusing patterns of large particles (size ratio 1/3) in square duct flows over a wide range of Re, by experimental and numerical studies. We have confirmed the appearance of the CCE pattern at low Re. An increase in Re was found to yield the CFECCE pattern, followed by the CFE pattern. 
(Author Not Attending)

KP1.00025: Development of a functional exvivo porcine heart system to test and improve heart valve repairing techniques Caroline George, Ali Heyat, Vrishank Raghav Fully functional heart valves are integral to a healthy heart. Defective valves cause regurgitation, decreased cardiac output, and heart failure. Developing improved methods of heart valve repair typically involves performing the procedure on a pig in vivo, as pigs’ hearts are anatomically and physiologically very similar to humans’. However, a porcine ex vivo heart model can provide a reliable intermediate step before in vivo procedures to save resources on initial testing. In this study, the ex vivo left heart model is designed, developed, and analyzed to test its ability to emulate an in vivo beating heart for surgical testing. A pulsatile pump was connected to an explanted porcine heart to mimic the physiological beating of the heart, and saline solution was pumped through the heart to mimic blood flow. Damage was induced on the heart valves. Hemodynamic parameters such as cardiac output and ventricular pressure were measured with flow and pressure sensors before damage, after damage, and after surgical repair to assess the model’s accuracy and the repair’s effectiveness. 

KP1.00026: Shockdriven mixing and turbulence Adam A Martinez, John James Charonko, Katherine P Prestridge Experiments using a powder gun driver are able to created Mach 9 shocks in xenon to drive RichtmyerMeshkov mixing of a xenonhelium interface. At the Los Alamos Neutron Science Center (LANSCE), proton radiography (pRad) we acquire 21frame movies of areal density of the mixing zone in the test section of the XeHe shock tube for two different initial conditions at the interface. Analysis shows differences in growth rate and in mixing region structure, and the imprint of the initial condition perturbations is visible throughout the entire sequence of the experiment. Future plans for improvement in the radiography signaltonoise and the initial condition configuration are also described.


KP1.00027: Rotor Wing Interaction at Low Reynolds Numbers Darnisha Crane, Mingtai Chen, James Paul Hubner The increasing interest in micro air vehicles (MAVs) due to the development of small microcontrollers, batteries and sensors has led to unique MAV designs incorporating aspects of fixedwing, flappingwing and multirotor systems capable of hovering and forward flight. Of interest in this research are tiltwing and tiltrotor designs. Although research has been conducted on large vehicles with these capabilities, little research has been performed on the MAV counterparts (Re ~ 100,000 and disk loading < 100 N/m^{2}). The objective of this research project was to build a test stand and measure the rotorwing interaction of a dualrotor configuration in hover above a flat plate representing a simple wing. Rotorwing height and rotorrotor separation can be set as well as rotor rpm. Surface pressures, motor thrust and motor torque are measured. The equipment was controlled and data was acquired using an inhouse LabVIEW code. Results will quantify the ground effect and potential loss of lifting force in hover for different rotor configurations. In future studies, these results will be used to validate computational models. 

KP1.00028: Vortex Shedding Analysis in the Wake of a Rotating Cylinder Trevor Berg, Amy W Lang, Leonardo Santos, Andrew Bonacci A rotating cylinder can be used to generate an adverse pressure gradient (APG) for flat plate boundary layer studies. However, there must be certainty that wake fluctuations do not pollute the baseline boundary flow. Previous research has studied vortex shedding in an effort to understand and predict the flow past a rotating cylinder. However, experiments were performed largely at lower Reynolds’ numbers. A DPIV study of six velocity ratios (VR) ranging from 0 to 3.85 which were tested at Re = 4114 and 5500. Results were consistent with previous studies. As VR increased, vortices remained in closer proximity to the cylinder, and they were increasingly deflected at an angle off to one side. It was observed that VR > 2.0 is the critical value at which vortex shedding is suppressed. During boundary layer studies, a ratio of VR > 3.5 is used to induce an APG and cause flow separation conditions. In addition, results show that by this point the wake of the cylinder has been largely deflected outward and away from the flat plate. These results help validate the use of a rotating cylinder as a means to induce an APG without its wake interacting with the boundary layer during flat plate studies. 

KP1.00029: Utilizing Raman Scattering to Explore the Nonequilibrium Thermodynamics of Plasma. Robert Dupont, Mruthunjaya Uddi, Rajagopalan Varadarajan Ranganathan We describe a nonintrusive method to measure the vibrational distribution and concentration of molecules in nonequilibrium plasma, such as O_{2}, CH_{4}, H_{2}, CO, and CO_{2}. This method utilizes Raman scattering to determine the chemical makeup and temperature of a sample of plasma. A 2cavity laser pulse stretching technique is used in this method to increase the amount of time it takes the laser pulse to pass through the sample. The 2cavity laser pulse stretching technique uses two beam splitters to split the laser pulse. One part of the laser pulse is then sent through a cavity created by a set of mirrors while the other part continues to the second beam splitter and second cavity. This technique triples the length of the pulse from approximately 20 ns to approximately 60 ns. The method originally used a Herriott cell to increase the number of passes the laser makes through the sample which would amplify the gathered signal. The cell that was created did not have a great enough vertical resolution for the tests so only one extra pass will be used. The method was used to collect Rayleigh scattering data from ambient air and will be used to collect Raman scattering data from ambient air and a methane flame in the near future. 

KP1.00030: Characterizing Plasma with the Utilization of a Langmuir Probe Emily Austein, Richard Branam, James Rogers The impact of iodine vapor and plasma on spacecraft materials can be tested in many ways; for example, a spacecraft materials setup involving their exposure to iodine vapor and plasma at a variety of temperatures and pressures. A common way to test them is by constructing a Langmuir Probe; this is used to characterize the plasma. Although there are many ways to construct a Langmuir Probe, this one will be made of tungsten wire as it is a hightemperature material, alumina tubing, and a bandstop filter. To characterize the plasma, the probe is inserted into the plasma using a holder constructed of aluminum, the holder contains four holes for data collection. While in the holder, the probe is inserted in and out of each hole to collect more data points and also spun with the use of a Stepper Motor Configuration. 

KP1.00031: HallEffect Thruster Performance Characterization Using a Torsional Balance Thrust Stand Anne Kary, Richard Branam, Connor Burleson, Colin Bennett A torsion balance microNewtonresolution thrust stand is used to characterize the performance of the University of Alabama microHall Effect Thruster (UA MHET). The thrust stand is capable of testing plasma thrusters that weigh several kilograms and measuring thrust at the μN level at steady state. For both calibration and testing, thrust is measured using a linear displacement sensor (LDS) laser. The thrust stand uses electrostatic plates for calibration, with the potential for use in active damping, and a vacuumcompatible, noncontact passive eddy current damper to reduce external noise. At the time of writing, this project is ongoing and only preliminary calibration data has been collected. The usefulness of the thrust stand will be shown by its ability to measure the thrust produced by the UA MHET and confirm results found by the original designer of the UA MHET, Matthew Warren. 

KP1.00032: Characterization and detection of highfrequency combustion oscillations in a rocket model combustor Hajime Shibuya, Tatsuya Hashimoto, Hiroshi Gotoda, Yuya Ohmichi, Shingo Matsuyama We present a numerical study on the characterization and early detection of highfrequency combustion oscillations on the basis of the theories of complex networks and synchronization. In this study, we deal with a cylindrical combustor with an offcenter installed coaxial injector as a liquid rocket model combustor. The turbulence network proposed by Taira et al. [J. Fluid Mech. 795, R2 (2016).] in which weighted networks are constructed by connecting each ﬂuid element to other ﬂuid elements, enables us to identify vortical interactions in a turbulent combustor [S. Murayama et al., Phys. Rev. E. 97, 022223 (2018)]. We observe a clear powerlaw decay in terms of the vertex strength in the turbulence network during combustion oscillations, indicating the presence of scalefree structure. In the transition process to combustion oscillations, the coherence structure begins to appear in the phase field consisting of pressure fluctuations p' and heat release fluctuations q'. The Kuramoto order parameter considering the mutual coupling between p' and q' [S. Mondal et al., J. Fluid Mech. 811, 659 (2017).] is valid for capturing the precursor of highfrequency combustions oscillations in a cylindrical combustor with an offcenter installed coaxial injector. 

KP1.00033: Blood Flow Downstream of a Dysfunctional Mechanical Heart Valve Nasibeh Mirvakili, Wael Saleh, Giuseppe Di Labbio, Lyes Kadem Dysfunctional mechanical heart valves cause mortality of a great number of patients around the world. One of the treatments is replacement of malfunctional heart valve with mechanical heart valve (MHV). Yet, thrombus formation threatens the functionality of the replaced valve. Although probability of thrombus formation is not high, it is one of the most severe heart complications. In this experiment, a system simulating a left heart including a siliconventricle fixed in an acrylic chamber, was used. The ventricle was contracted as a result of the pushed fluid by a piston inside the simulating system. The fluid was a solution of water and glycerol, 60% and 40%, respectively with a density of 1090Kg/m^{3} and a dynamic viscosity of 4 x 10^{2 }Pa.s. Time resolved PIV (Particle Image Velocimetry) measurement was taken along the central plane of the left ventricle. The experiment was repeated for four different valve conditions. Velocity profiles were obtained and normalized with respect to the average velocity of corresponding profile. Viscus energy dissipation and accumulation of sheer stress were computed for all the four cases. The most severe case (one blocked leaflet) showed the highest velocity, energy dissipation and accumulation of shear stress. 

KP1.00034: Steady State Analysis of a Diesel Engine Avery Pendley, Joshua Bittle, Mason Moore, James Cook, Allen Parker, Spencer Hall The diesel engine powers nearly every heavyduty truck on the globe. During the commissioning of a new Cummins ISX15 engine installation, a heavyduty engine dynamometer is used to characterize the engine performance at a range of steadystate operating conditions (different speeds and loads). After adding significant new instrumentation, the efficiency and energy split distribution of the engine was acquired at each condition. The specific measurements taken during engine operation were input into a separate program in which the various energy transfers were all accounted. This includes fuel energy input, shaft work output, heat loss to the coolant, heat loss to the exhaust, and estimated heat lost through radiation. Through this data and calculations, the way by which diesel engines achieve high efficiency in general as well as higher efficiency at different speeds and loads was assessed. General trends from the data include a higher efficiency and less heat loss to the radiator at larger torque, as well as a larger exhaust energy content at a higher speed. Future testing will include a larger range of speeds and loads to further bolster these trends and establish concrete data of engine efficiency. 

KP1.00035: Container shape dependence of heat transport in high Prandtl number fluid RayleighBénard convection Hamed Ziad Ammar, Jessica Imgrund, Stephen R Johnston, Enrico Fonda, Katepalli Raju Sreenivasan, Devesh Ranjan Extensive progress has been made in the past to study RayleighBenard convection (RBC) and the inherent heat transport scaling in circular and square crosssectional test cells of various aspect ratios. The internal flow pattern in these crosssectional geometries has been observed to be different, though the heat transport remains largely unaffected for low Prandtl number (Pr) fluid RBC. However, limited studies using highPr fluids have shown that the heat transport relationship can be influenced by manipulating sidewall boundary conditions. We use a new facility designed for interchangeable test cells to observe heat transport in highPr fluids for different crosssectional geometries to better understand these differences. We present results at Rayleigh numbers up to 10^{9 }for circular and square crosssectional test cells with an aspect ratio 0.75, and using [O(10^{3})] Prandtl number working fluid. 

KP1.00036: Dynamics of RayleighTaylor instability in selfsimilar regime Prasoon Suchandra, Mark M Mikhaeil, Gokul Pathikonda, Devesh Ranjan RayleighTaylor (RT) instability presents itself in a variety of phenomena. Most of these applications involve complex physics and vary dramatically in length and time scales. In this work, results from statistically steady RT experiments are presented that were performed in the convectivetype twolayer gas tunnel facility at the Georgia Institute of Technology, using air as heavier fluid and airhelium mixture as lighter fluid. Data is collected at a moderately high Atwood number (~ 0.7) and high mixing Reynolds number (> 20000). Velocity profiles and Reynolds stress profiles are displayed across the mixing layer. To understand the selfsimilar nature of this flow, collapse in turbulent quantities is examined with appropriate scaling factors, and characteristics such as selfsimilar mixing growth rate are computed. Calculations of probability density functions and energy spectra are made to further characterize the flow. Experiments like this provide modeling community with large data set of relevant turbulence statistics and explain the nature of turbulence in anisotropic, inhomogeneous flows. 

KP1.00037: Horizontal motion of columnar vortices formed in rotating thermal convection Daisuke Noto, Yuji Tasaka, Takatoshi Yanagisawa, Yuichi Murai We investigated horizontal motion of columnar vortices, flow structures having coherence along the rotation axis, observed in rotating thermal convection by laboratory experiments. Thermochromic liquid crystals were employed to visualize and detect vortical structures in horizontal crosssections with the parameters Ra = 1.0 × 10^{7} and Ta = 1.0 × 10^{7 } 1.0 × 10^{8}. Two different size of cylindrical fluid layers filled with water (Pr ∼ 7) were used to investigate vortex motion under the condition with or without centrifugal force effect. The method to detect and track vortex motion we established made it possible to conduct longtime interval photographing, without obtaining velocity or vorticity fields. Thanks to this and the long time measurements O(10^{3} s), some statistical analyses to clarify the diffusive motion of columnar vortices had been achieved. Interesting characteristics of columnar vortices, such as generation, disappearance, merging, repellence, and limitation of lifetime, enable them to behave as like anomalous diffusion. 

KP1.00038: DFD POSTERS


KP1.00039: A Correlation Study of Wind Tunnel Wall Correction in Low Speed Wind Tunnel Younseok Choi, Sanghyun Lee In closed section wind tunnel, the flow field around the test model changes due to the testsection being surrounded by the wind tunnel wall. Therefore, the correction of aerodynamic characteristics changes due to the wall affects the accuracy of the test results. It is generally known that a correction to the wall effect is required if the blockage ratio is greater than 5%. There are classical methods, wall pressure measurement method, CFD application method, and adaptive wall method, but the classical method and the wall pressure measurement method are generally used for the correction of the wall effect. If the size of the measurement part is large like the middle size wind tunnel, the blockage ratio is less than 5% and the correction is not necessarily required. However, if the size of the measurement part is small like the small size wind tunnel, blockage ratio often exceeds 5%. In this study, the same test was conducted on the small size wind tunnel and the middle size wind tunnel in the Air Force Academy, and various comparisons were made and compared with the corrected experimental results. We tried to find the applicable correction method for the small size wind tunnel by correcting the results in the small size wind tunnel with the middle size wind tunnel results. 

KP1.00040: Aerodynamics of SelfDocking UAS on Tether Dominic Christian DiDominic In the past several years, the interest in the use of autonomous unmanned aircraft systems (UAS) has exponentially increased. However, battery capacity technology has not kept pace for the longer flight times required for many applications. Therefore, many UAS operators are turning to power by tether systems. The use of tethering is a concern for operators as the introduction of a freeswinging pendulum below a UAS during crosswinds raises concern for stability control of the vessel. The following experiments investigate the ability of a UAS to dampen the oscillation of the tether as a result of the downwash flow from the UAS’ propellers while landing. Experiments are conducted using a large octocopter UAS in both indoor and outdoor environments to record frequency and amplitude data of an oscillating tether in a variety of crosswind velocities. That data will then be compared to data gathered at similar mean air velocities, however, with the addition of propeller downwash equivalent to what is expected from a UAS during landing/docking. Qualitative and quantitative data from these experiments will be useful in determining the optimal approach and tethering mechanism for a selfdocking tethered UAS. 

KP1.00041: Experimental Study on a Parachute for CanSAT Kitak Won, Sanghyun Lee CanSAT parachutes must fall down at lower speed than normal ones, since they should be simulating satellite missions during their falling. They also should be deployed after the line is fully extended, and have stability against swing motion. A wind tunnel experiment was carried out for the design of CanSAT parachute satisfying these conditions. Parachutes with the desired terminal speed, that is, the same cross sectional area, were produced by limiting as the cruciform and round shape, which are simple forms of manufacture. As the design parameters, different armratio and linelength ones are included in our experiment. In order to measure the drag force against the speed in the steady state, a wire type support was made and a load cell mounted at the center of the support. Also using highspeed camera, the deployment characteristics were investigated. The results show that all of the parachutes manufactured satisfy the required deployment characteristic and that there is a significant difference in the drag force depending on the shape. 

KP1.00042: Interactions between upstream turbulent flow and quadrotor thruster controller performance Ningshan Wang, JohnMichael Velarde, Mark N Glauser Ningshan Wang, Jacob Connors, JohnMichael Velarde, Mark Glauser—The upstream velocity field of a quadrotor UAV and its thruster controller performance are investigated in experiments at Syracuse University. These experiments are conducted in SU’s subsonic wind tunnel and Indoor Flow Lab. This research targets providing more details on the dynamics of this interaction in order to support the development of more robust quadrotor controllers when exposed to turbulent environments. The quadrotor UAV is exposed to turbulent flows, with different intensities, length and time scales, to gain the interaction information under a variety of conditions. Characterization of the upstream flow field is by hot wire and PIV. A 6DOF balance is utilized to capture simultaneously, along with the flow measurements, the forces and moments experienced by the quadrotor UAV. The interactions of these forces and moments with the input turbulent characteristics are analyzed using frequency domain approaches. 

KP1.00043: Leadingedge Vortices Over Sweptback Wings William B. Lambert, Mathew J. Stanek, Roi Gurka, Erin E. Hackett Micro air vehicles are used in a myriad of applications, such as transportation and surveying. Their performance can be improved through study of new wing designs and lift generation techniques including leadingedge vortices (LEVs). Observation of natural fliers, e.g., birds and bats, has shown that LEVs are a major contributor to lift during flapping flight, and the common swift (Apus apus) has been observed to generate LEVs during gliding flight. Particle image velocimetry experiments were performed in a water flume to measure flow over wings with nonlinear sweep (swiftlike wing), linear sweep (delta wing), and zero sweep (rectangular wing). Experiments were performed at three spanwise planes at four angles of attack for a chordbased Reynolds number of 25280. Streamlines, vorticity, swirling strength, and Q criterion, were used to identify LEVs for each experiment. The results show that LEVs exist at attack angles of 20° and 30° for both the delta and swift wing geometries and that the vortex evolution along the wing span is similar for the two wing geometries. The similar vortex structure over both wings suggests that multiple swept leadingedge geometries are capable of creating similar LEVs. 
(Author Not Attending)

KP1.00044: Flexible Airfoils and their effect on Flow Separation David Fariyike, David W MacPhee, Kellis Kincaid, Lalit Roy, Roohany Mahmud In the US alone, there are 5,000 planes in flight at any given moment and 52,000 wind turbines in operation. Any object that is subject to high wind speeds or varying attack angles has the potential to have flow separation. Flow separation increases drag which results in a less efficient aerodynamic system. Previous research has shown that active shape changing airfoils can reduce flow separation. However, since the shape change is active it introduces parasitic cost to the system, detracting overall energy capture. In this project, a passive method of reducing flow separation with flexible airfoils is investigated. The flexible airfoils have shown to increase airfoil performance as compared to a rigid design. While the flexible airfoils can increase airfoil performance, it cannot withstand the same wind speeds as its rigid counterpart. The performance improvement is speculated to be a result of boundary layer reattachment post the point of stall, reducing the flow separation and increasing lift when compared to the rigid design. 

KP1.00045: Full factorial study of the power output of sidebyside piezoelectric harvesters in various types of fractal gridgenerated turbulence Kevin Ferko, Nicholas Chiappazzi, Amir DaneshYazdi, George Lesieutre While the majority of the literature in energy harvesting is dedicated to resonant harvesters, nonresonant harvesters have not been studied in as much detail. In this study, the power output of two sidebyside fluidic harvesters from three passive fractal grid configurations (fractal square, fractal ‘I’, and fractal cross patterns) with similar blockage ratios is considered. Fractal grids have been shown to significantly increase the turbulence generated in the flow which is the source of the vibration of the piezoelectric beams. The influence of four parameters has been investigated in a fullfactorial experimental study: Beam lengths and configurations, mean flow velocity, distance from the grid and gap between the two beams. Results show that the piezoelectric harvesters in all three fractal grids are capable of producing a larger power output per beam compared to the classical rectangular grid pattern with a smaller blockage ratio (and therefore pressure loss), allowing for a potentially significant increase in the efficiency of the energy conversion process. 

KP1.00046: Are SidebySide Piezoelectric Harvesters a Feasible Power Source in LowIntensity Grid Turbulence? Kevin Ferko, David Lachendro, Andrew Bradley, Amir DaneshYazdi Resonant fluidic harvesters can typically be tuned to the frequency of the flow, so they yield a larger power output compared to their nonresonant counterparts. In order to explore increasing this output for nonresonance harvesters, a feasibility study has been performed to analyze the behavior of two sidebyside piezoelectric harvesters in lowintensity (less than 1%) gridgenerated turbulence with respect to beam configurations, mean flow velocity, distance from the grid and separation between the two beams. Experimental results show that the potential for energy harvesting is perhaps not as great in the low meanvelocity flow as it is for the higher speed cases which are accompanied by flutter, but the sidebyside piezoelectric beams display potential for use as turbulence sensors at low speeds. 

KP1.00047: Initial Study on RCS and Aerodynamic Characteristics relative to the Shape of Airfoil Yujung Yoon, Sanghyun Lee An unmanned aerial vehicle (UAV) becomes gradually important. Especially in the future warfare, operation of UAVs is a key role for victory. In order to make the UAV undetected by an enemy radar and fly efficiently, two essential factors need to be considered. The first factor is radar cross section (RCS), which is a measure of how detectable a UAV by an enemy radar. A larger RCS indicates that the UAV is more easily detected from the enemy radar. The another factor is a lifttodrag ratio, which is used for analysis aerodynamic efficiency of the UAV. In this study, we calculate the RCS using several equations and obtain the lifttodrag ratio by conducting wind tunnel test. We expected that stealth ability and flight efficiency of the UAV are closely connected curvature the front area of airfoil. Therefore, the calculated RCS and the obtained lifttodrag ratio are relative to the shape of airfoil. Finally, we find the most suitable shape of airfoil by considering both the RCS and aerodynamic characteristics. 

KP1.00048: General relativistic manifestations of orbital angular and intrinsic hyperbolic momentum in electromagnetic radiation James Strohaber General relativistic effects in the weak field approximation are calculated for intense electromagnetic LaguerreGaussian beams. The current work is an extension of previous work on the precession of a spinning neutral particle in the weak gravitational field of an intense optical vortex. Here the metric perturbation is extended to all coordinate configurations and gravitational effects from intrinsic spin and hyperbolic momentum are considered. The final metric perturbation reveals framedragging effects due to intrinsic spin angular momentum (SAM), orbital angular momentum (OAM), and spinorbit (SO) coupling. When investigating the acceleration of test particles in this metric, an unreported gravitational phenomenon was found. This effect is analogous to the motion of charged particles in the magnetic field produced by a current carrying wire. Further calculations showed that the gravitational influence of SAM and OAM only affected testrays traveling perpendicular to the intense beam and from this a gravitational AharonovBohm analog is pursued. J. Strohaber, "General relativistic manifestations of orbital angular and intrinsic hyperbolic momentum in electromagnetic radiation," arXiv preprint arXiv:1807.00933(2018). 

KP1.00049: Vortex Shedding behind a Seal Whisker and VortexInduced Vibration Jodi Turk, Wei Zhang, Sang Joon Lee Harbor seals can track their prey by detecting minute disturbance of the ambient water solely by their whiskers, instead of visual and auditory senses. The outstanding hydrodynamic capability of seals’ whiskers is attributed to the unique undulating threedimensional morphology of the whisker. Research using whiskerlike models show that the undulating morphology suppresses vortexshedding in the wake and reduces vortex induced vibration (VIV), especially when the major axis of the whisker is aligned with inflow (angle of attack or AOA = 0°). However, few laboratory studies have been conducted to reveal the interaction between the wake flow and the real seal whisker, which has a natural variation in length and size as well as a twist along the length. This work uses highspeed particle imaging velocimetry (PIV) to analyze the vortex shedding generated by a real elephant seal whisker (undulating morphology) and compare it to that of a California sea lion (smooth morphology) at Reynolds number of 400. The vortexinduced vibration of the whiskers is also measured at two AOAs, 0° and 90°. The current work can provide insights on the effects of the inflow direction on the flowwhisker interaction, and development of highperformance whiskerinspired engineering components. 

KP1.00050: The interaction between fluid flow and biofilm growth in fractured rock Kayla Lewis We investigate the interaction between fluid flow and biofilm growth in fractured rock, with a view toward understanding the impacts of this interaction on seafloor hydrothermal fluid venting. We present a preliminary model that predicts the conditions under which a biofilm may attain steady state, the thickness of such a steady state film, and the effect of the film on the permeability of the porous rock matrix as well as on interstitial fluid velocities. In particular, the model predicts that a biofilm can only attain a stable thickness when a precise relationship holds between parameters representing the fluid velocity, bacterial substrate ingestion, and sloughing off of the film into the fluid stream. Conversely, when this condition does not hold, the biofilm either grows to fill all available space or no biofilm can be supported. 

KP1.00051: Measuring the Deformation of Adsorbed Particles using the Quartz Crystal Microbalance jurriaan gillissen, Joshua A Jackman, Seyed Tabaei, Bo Kyeong Yoon, NamJoon Cho We numerically simulate the hydrodynamic force on ellipsoidal particles, adsorbed on an oscillating surface. From the simulation results, we fit a relation between this force and the particle aspect ratio and the oscillation frequency. The relation is used to extract shape information from quartz crystal microbalance (QCM) measurement data of the adsorption of 70 nm liposomes, whose shape is changed by varying the osmotic pressure difference across the liposomal bilayer. We thereby determine the membrane bending energy, consistent with literature values. 

KP1.00052: Lumped Parameter Modeling of Cardiovascular and Cerebrovascular Hemodynamics Tyler Compher, Vrishank Raghav Cardiovascular disease is the leading cause of death in the United States, affecting approximately 17.9 million people in 2015. This results in huge socioeconomic burden on the US with over $500 billion spent annually. While human and animal model studies yield the best results, computer models of the cardiovascular system provide researchers with a simpler alternative to study hemodynamics in order to better understand and treat cardiovascular disease. The goal of this work was to develop a coupled cardioandcerebrovascular computer model that would reproduce physiologically accurate pressures and flowrates in arterial segments. The model could then be used to investigate phenomena resulting from the coupling of the cardioandcerebrovascular system. An analog of an electrical circuit was used to simulate blood flow. The flowrates and pressures calculated using this model were then compared to clinical measurements to validate the model. The resulting pressures and flow rates matched those that are measured clinically, validating the model. This model can be used to investigate the relationship between the cardioandcerebrovascular system. 

KP1.00053: Studying Peripheral Artery Disease Treatment With HighResolution, Massively Parallel CFD Simulations Adebayo Adebiyi, Lynne M. Koweek, Leila Mureebe, Amanda Randles Peripheral arterial disease (PAD) refers to the impairment of blood flow to the peripheral arteries due to atherosclerosis. Clinicians rely on experience and established guidelines to develop treatment plans for patients undergoing revascularization because of the risk of limb loss. However, there has yet to be a consensus on the optimal treatment therapy. The anklebrachial index (ABI) is a noninvasive, accurate method to assess the extent of PAD and response to therapy. Furthermore, endothelial shear stress (ESS) have been implicated in atherosclerotic pathologies. Hence, a patientspecific ESS and ABI pre and postintervention may provide insight into the mechanisms driving treatment outcomes for an individual patient. In this study, we develop a CFD framework, that utilizes 3D geometry of the major arteries generated from Computed Tomographic Angiography (CTA) of a cohort of patients, to compute patientspecific ABI and holistic ESS. The predictions from the framework were validated by comparing the computed and the measured relative ABI pre and postintervention. The major traditional revascularization procedures were simulated to predict the patientspecific response. This work lays the critical foundation for a more evidencebased clinical decisionmaking. 

KP1.00054: Intracranial Aneurysm Correlations: Vessel Wall Imaging, Hemodynamics, and Histology Kurt Sansom, Mahmud MossaBasha, Chun Yuan, Alberto Aliseda Unruptured intracranial aneurysms (UIA) are evaluated with angiography, or noninvasive (MRI, CT). Current techniques present limitations on the resolution with which the vessel wall characteristics can be measured, presenting a major challenge to differential diagnostic of cerebral vasculopathies. A new combined approach is presented that incorporates patientspecific imagebased CFD models with VesselWall MRI (VWMRI). Comparisons of the VWMRI measurements, evaluated for the presence of wall enhancement and thinwalled regions, against CFD metrics such as wall shear stress (WSS), and oscillatory shear index (OSI) are used to understand how the new imaging technique developed can predict the influence of hemodynamics on the deterioration of the aneurysmal wall, leading to rupture. Additionally, histology of each resected aneurysm is evaluated for inflammatory features to independently validate the VWMRI and CFD. The results elicit the complexity associated with unstable wall change evaluation in UIAs and potential use for combined modalities (VWMRICFD) to support clinical monitoring and intervention decisions. 

KP1.00055: Shear Measurements of Cerebrospinal Fluid Flow in Mice Edna R Toro, Jeffrey Tithof, Humberto Mestre, Maiken Nedergaard, Douglas H Kelley Amyloid beta 42 is found in plaques in the brains of Alzheimer’s disease patients and is believed to be a factor in damaging and killing neurons. The process of accumulation of amyloid beta 42 leading to the formation of plaques is not well understood. One mechanism that has been correlated with amyloid protein aggregation is molecular distortion due to shear in fluid flow [Trumbore, Journal of Alzheimer’s Disease 59, 543557 (2017)]. After acquiring images using twophoton microscopy, we performed particle tracking velocimetry to obtain quantitative measurements of cerebrospinal fluid flowing within spaces around arteries in the brains of living mice. We determined the velocity and shear rate in the cerebrospinal fluid with high resolution by applying phase averaging over the cardiac cycle. Our measurement of shear rate offers a potential mechanism by which fibril formation rises leading to an increased risk for Alzheimer’s disease. 

KP1.00056: A novel gust generator design to study the aerodynamic response of birds to vertical gusts Mike Wietstruk, Paul Swiney, Vrishank Raghav Recently there has been significant interest in the development of uninhabited aerial vehicles (UAVs) for civilian and military applications. However, a primary limitation to the widespread adoption of UAVs is their inability to perform well in gustladen environments. This project adopts a bioinspired approach to improve UAV design by collaborating with the Southeastern Raptor Center (SRC) to study the aerodynamic response of birds exposed to vertical gusts. To study the aerodynamic response of birds in a controlled environment, a novel gust generation device was developed. A commercially available air curtain with variable gust speed was procured and characterized. While gust speed was sufficiently high, it was observed that a nonuniform gust was produced across the length of the device. Modifications in the form of diverging ducts were incorporated to achieve a uniform gust speed of 6.3 ± 0.2 m/s. This gust generation device will be introduced in the flight path of a redtailed hawk that is currently housed at the SRC. A combination of onboard sensors and highspeed imaging will be used to study the response of the hawk to this gusty aerodynamic environment. An improved understanding of bird flight mechanics in gusty conditions will allow for improved design of UAVs. 

KP1.00057: Underwater navigation with an elastic plunging fin. Ersan Demirer, Peter Derek Yeh, Alexander Alexeev Fish can effectively achieve gradual turning and escape maneuvers using multiple fins. However, for a robotic fish it might be advantageous to use a single fin to generate thrust as well as control the fish navigation. We solved the fluidstructure interaction problem using threedimensional computer simulations based on the lattice Boltzmann and lattice spring models to investigate turning strategies for an oscillating rectangular elastic fin actuated near its first natural frequency in a Newtonian fluid. We probe how to produce pitching and yawing moments by altering the fin plunging. The first strategy uses plunging with asymmetric stroke velocities to create pitching. The second, combines plunging with a twisting motion to create a yawing moment. In both cases, net lateral forces and moments are generated. We found that in the case of asymmetric plunging an increasing velocity ratio between strokes led to increased magnitude of force and turning moment. We identified the optimum correlation between the phase angle and the rotation amplitude maximizing the yaw moment, in which case the phase must be tuned so that the instant of the maximum force overlays with the instant of the maximum rotation. 

KP1.00058: Lagrangian coherent structure analysis of swimming jellyfish reveals tradeoffs between efficient swimming and effective foraging Colin J Stewart, Gregory Krummel, Shashank Priya Many jellyfish species benefit from passive energy recapture (PER), a secondary swimming acceleration that occurs if the animal pauses between contraction cycles. Utilization of PER can dramatically reduce the cost of transport (COT)—e.g. by ~50% in Aurelia aurita. However, many species do not take full advantage of the phenomenon. Oblate jellyfish, which rely on the fluid flow generated by their bell contractions for both propulsion and feeding, keep their pauses short, truncating the PER benefit. Here, we investigate the hypothesis that longer pauses increase PER but reduce prey entrainment rates. CFD simulations of freeswimming Aurelia aurita with various pause durations show varied amounts of PER benefit and propulsive energy savings. We compare these savings to the changes in prey clearance rate, found from Lagrangian coherent structures via the finitetime Lyapunov exponent (FTLE) field, and estimate the associated energy gained from feeding. The tradeoffs between efficient swimming and effective predation are key to understanding the cosmopolitan success of jellyfish despite their simple biomechanics. 

KP1.00059: Long tentacles and oral arms alter feeding currents generated by the jellyfish Cyanea capillata Gregory Krummel, Colin Stewart, Shashank Priya During development from larvae to adults, scyphozoan jellyfish undergo changes in morphology concomitant with the increase in Reynolds number of their fluid environment. Tentacles and oral arms develop as the wakes of cruiseforaging jellyfish become inertially dominant, characterized by vortices that induce feeding currents and transport prey to these trailing preycapture surfaces. However, tentacles can reach far behind jellyfish, and it is unclear how effective these captures surfaces are when they extend past the vortex wake. Here we quantify changes in flow structures around a 50 cm, freeswimming robot model of Cyanea capillata with the addition of artificial tentacles and oral arms. We estimate the tradeoff between decreased swimming efficiency and the increase in prey clearance rate that tentacles provide. Velocity fields measured with DPIV are used to identify changes in Lagrangian coherent structures (LCS) that transport prey to tentacles. 
(Author Not Attending)

KP1.00060: Behaviour of an oscillating chiral squirmer in a chemical gradient Ruma Maity The rotational motion in addition to translation is an advantage of the chiral squirmer over a simple squirmer in such a way that the chiral one can change it's orientation in any arbitrary direction. This is an important property required for the body to sense the external chemical gradient. The chiral squirmer considered here performs an oscillatory motion in the medium which can be captured with the aid of a time dependent surface slip velocity [1]. In presence of the gradient the oscillatory motion of the squirmer is altered due to the modification in the coefficients of the slip velocity and it starts to move towards the direction of the gradient. Here we have studied, how the net displacement of the body at the end of a complete cycle of oscillation towards the direction of the gradient depends on the strength of the gradient and the frequency of oscillation. This study can be useful to design artificial oscillating swimmers which are capable to chemotax. (Ref. 1. R. Maity and P. S. Burada, to be submitted.) 

KP1.00061: Designing active microcapsules for particle capture Svetoslav Nikolov, Alberto FernandezNieves, Alexander Alexeev The large topological changes of microgels, observed through the volumephase transition, gives these gels the unique ability to induce transport, and force solvent in and out of the constituent polymer network. In our work we use dissipative particle dynamics to study how these materials can be exploited to create a novel microdevice for particle capture. By embedding a spherical microgel in a perforated capsule we leverage these shape changes to selectively capture nanoparticles from particlerich solvent. Upon application of an external stimulus the gel swells, expanding through the perforated holes and contacting the external solvent. Removal of the external stimulus collapses the microgel into the shell interior, bringing in particles from the external solution. The area around each of the perforations is functionalized with a polymer brush which is used to achieve chemical gating, when the gel is in the collapsed state. We study how the capture rate depends on the swelling period and gelnanoparticle interactions and we quantify the optimal swelling period which maximizes capture rates. 

KP1.00062: Supersonic oblique shockwave boundary layer interaction of free stream shockwave perturbations with supersonic ground effect aerodynamics. Arnoldo Jaquez 

KP1.00063: Abstract Withdrawn A roughwall boundary layer over various wall roughness geometries is investigated using a highspeed PIV and refractive indexmatching (RIM) of the wall with the working fluid. This index matching enables measurement of nearwall scales within the roughnesssublayer with high spatiotemporal resolution, and the subsequent investigation of scale interactions between the large and small scales. Flow was measured in two fields of view with different magnifications to capture large and small scales simultaneously. Besides the baseline smoothwall boundary layer measurements, two types of roughness geometries are considered – (1) a hexagonallypacked hemispherical roughness and, (2) a multiscale roughness with characteristics similar to a damaged turbine blade. Innerouter modulation interactions investigated with these well resolved measurements indicate that there might a stronger correlation between the scales in boundary layers over roughwalls when compared to the smoothwalls. We identify the differences in the structure of the same between the smooth and rough conditions, and the effect of multiscale geometry on the latter. 

KP1.00064: Roughness Effects on the laminar separation bubble Chao Jin, Hongwei Ma, Bowen Xu, Qiuming Li Laminar boundary layer separation represents a source of losses that sensibly affects the aerodynamic performances. The roughness surface has been widely used to control the separation, while the entropy generation and the turbulence production mechanisms due to the roughness element are not clear. To explore those mechanisms, this paper investigates the boundary layer development on the flat plate using highresolution particle image velocimetry (PIV) in the water tunnel. The flow past the flat plate under an adverse pressure gradient and subject to the roughness surface. The entropy generation rate is analyzed by proper orthogonal decomposition (POD) applied to the measurements. The observations from this work show that, the roughness accelerates the transition process and can decrease the size of the separation bubble. The mean viscous dissipation contributes significant portions of entropy generation at low order modes and the high order modes contain most the turbulent contributions. 

KP1.00065: Dynamics of a Laserinduced Bubble Near a Convex Free Surface Zhigang Zuo, Shengji Wu, Zibo Ren, Shuhong Liu This paper experimentally documents the behavior of a laserinduced bubble near a convex paraboloidal free surface with different vertical radius of curvatures, generated in a rotating cylindrical water flask. Due to the strong influence of the free surface, the bubble forms a microjet outwards the free surface when it collapses. And the nondimensional bubble collapse time, T_{c}/T_{c}’, is smaller than 1, where T_{c} is the bubble collapse time and T_{c}’ is the Rayleigh time of bubble collapse with an equivalent maximum radius. As the relative distance between the bubble center and the free surface, h/R_{max}, decreases, T_{c}/T_{c}’ decreases, which is different with the bubble behavior near a flat rigid boundary, where h is the distance between the bubble center and the flat free surface or the convex free surface center, R_{max} is bubble equivalent maximum radius. Meanwhile the convex free surface provides a focusing mechanism to the splash on the free surface when bubble collapses. The splash gets a higher velocity when r_{s}/R_{max} decreases. 

KP1.00066: Towards a durable polymeric internal coating for diabatic sections in heat pipes Joel de Coninck, Marco Marengo, Fabio Villa In this work the effect of surface wettability in pool boiling heat transfer is studied. The pool boiling phenomena is characterized by three important parameters: onset boiling temperature (T_{ONB}), the heat transfer coefficient (HTC) and the critical heat flux (CHF). All these parameters are influenced by the wettability characteristics of the surface. This work analyses the effects of surface wettability on these three parameters and proposes a new superhydrophobic polymeric coating which can have a very important effect in improving the heat pipe startup power load and increasing the thermal performance of heat pipes when the flux is lower than the critical heat flux. 
(Author Not Attending)

KP1.00067: Cavitation bubble induced wall shear stress Qingyun Zeng, Silvestre Roberto GonzalezAvila, ClausDieter Ohl The shear flow generated by the collapse of a cavitation bubble near a rigid boundary is relevant in surface cleaning and cell membrane poration among other applications. However, neither the spatiotemporal distribution nor the magnitude of the shear stress are well known. Here, we report on recent numerical simulations of the wall shear stress induced by a single cavitation bubble. The simulation is done based on a compressible twophase Volume of Fluid (VOF) solver from the OpenFOAM framework. The numerical results show good agreement with the experimental results. The flow region with constant shear rate in the boundary layer is reproduced with a locally refined mesh spacing Δx=0.05 μm. Very high stresses of 100 kPa are found during the early spreading of the highspeed transient jet from the collapsing bubble. Later, the main spreading flow and the reexpansion of the toroidal bubble together produce a vortex ring, which stabilizes the flow and thereby slows down the decay of the shear stress. In particular, a spatiotemporal map on the wall shear stress is provided, which summarizes the complex distribution of the shear stress on the solid boundary.


KP1.00068: Numerical simulations of an acousticallydriven bubble near a wall: analysis of the growth and collapse with standoff distance Sid BECKER, Bradley Boyd 

KP1.00069: Abstract Withdrawn Simulation of interaction of strong shocks and turbulence is an important computational problem which could result in the development of highwavenumber irregularities and discontinuities. These irregularities and discontinuities stem from nonlinear convective terms in the Euler and NavierStokes equations. In this study, we use the observable NavierStokes equations, to simulate this flow. In the observable equations the regularization is already applied in order to obtain the governing differential equations before any discretization is performed. For the shockturbulence interaction (STI) problem, observable methodology provides comparable results with the best available Large Eddy Simulation cases. Additionally, to study the effects of density variations on STI the results corresponding to an upstream multifluid mixture are compared with the results of singlefluid case. The effect of observability length scale in turbulence amplification by the normal shock wave and the reduction in turbulence length scales are also investigated and compared with other techniques available in the literature. 

KP1.00070: Irregular configurations of shock wave impingement on shear layers Cesar Huete, Daniel MartínezRuiz, Pedro J. MartínezFerrer, Daniel Mira This work examines the interaction of a shear layer separating two uniform supersonic streams of Mach numbers M_{1} and M_{2} with an oblique shock approaching at an incident angle σ_{i}. The development considers the outer problem of oblique–shock impingement on a supersonic vortex sheet of infinitesimal thickness, for which the region of existence of regular shock refractions with downstream supersonic flow is delineated in the parametric space (M_{1}, M_{2}, σ_{i}). NeumannHenderson plots are employed to characterize the family of solutions involving regular and nonregular configurations. Theoretical tools and highfidelity DNS are employed to resolve the evolution of the complex structures present in the flow. The massivelyparallel finitedifference code CREAMS is being used to solve the unsteady, twodimensional set of compressible Euler equations for multicomponent gas mixtures. The code accurately reproduces the expected regular interactions and provides the evolution of nonregular unstable configurations. 

KP1.00071: Experimental Investigation of Shock Wave Interaction With Various Boundary Layer Configurations Abdulaziz Alanzi In this study, experiments are carried on different boundary layer structures, using Schlieren techniques, Particle Image Velocimetry (PIV), Pressure taps and optical sensors. The tests are performed in a supersonic wind tunnel on an elliptic flatplate leading edge with finite thickness, a sharp flatplate leading edge with finite thickness and a cone attached to a circular cylinder, all the tests are carried in a Mach 2 freestream flow where the shock is generated. The shock wave boundary layer interaction (SWBLI) is studied in terms of the interaction behavior. The primary goal is to investigate flow characteristics upstream, downstream, and at the shockinduced separation, the shock position, the collected pressure data and the frequency distributions of each structure, and this is to identify the flow pattern of each boundary layer and to study how geometrical modifications influence the flow as well as the SWBLI. The flow is visualized using a Schlieren imaging system and the images captured are investigated using optical sensors that are proposed to make turbulence measurements. Boundary layer characteristics are presented through experimental results. 

KP1.00072: SemiExtrapolated Finite Difference Schemes: Accuracy and Consistency Sheila Whitman, Mikayla Feldbauer, Andrew Brandon When solving partial differential equations, finite difference methods are a popular choice. Several factors come into play when choosing a finite difference method, such as stability, computational cost, accuracy, and consistency. In response to the small stability regions of explicit methods and the computational cost of implicit methods, we’ve developed a novel discretization technique (semiextrapolation) that generates explicit schemes from implicit schemes by applying extrapolation to the implicit schemes in an unconventional fashion. Semiextrapolating can lead to improved stabilities as compared to the stabilities of analogous explicit schemes, however, consistency and accuracy can be affected by semiextrapolation. In our presentation, we’ll discuss our semiextrapolation technique and introduce several semiextrapolated discretizations of the Advection Equation and the AdvectionDiffusion Equation. We’ll then analyze the consistency of these semiextrapolated discretizations, compare their accuracies against the accuracies of several common discretizations, and discuss how stability constraints and choice of extrapolation stencil both influence the consistency and accuracy of semiextrapolated schemes. 

KP1.00073: MPI Parallelization of incompressible thermal flow solver for natural convection problems KiHa Kim, Xiaomin Pan, JiHoon Kang, JungIl Choi We perform MPI parallel implementation of incompressible thermal flow solver for efficient numerical simulations of natural convection problems. The numerical scheme for solving the thermal flow is based on the monolithic projection technique (Pan et al., 2017, J. Comp. Phys.), decoupling of momentum and energy equations by approximate LU decompositions. The approximate factorization technique is also applied to segregate the equations in each direction. The Poisson equation for the pressure is solved using the Fourier diagonalization technique for fast computations. The computation domain is decomposed with penciltype blocks and the information of each subdomain is interexchanged using MPI_Alltoall communication. The data packing/unpacking in threedimensional array data communication is employed based on the derived data type and subcommunicator for a better scalability. We investigate the parallel performance on simulating RayleighBenard convection problems. Detailed results for parallel performance will be presented at the meeting. 

KP1.00074: Largeeddy simulation of flow past a rectangular block attached to a sidewall Seokkoo Kang Largeeddy simulation (LES) is conducted for flow past a rectangular block installed in an openchannel flume. The LES results are compared with the measurement obtained using Acoustic Doppler Velocimetry and showed good agreement. The LES shows that the mean flow structure around and in the wake of the spur dike is highly complex and threedimensional. Specifically, flow upstream of the spur dike is featured by a vortex system near the bed, another vortex system beneath the free surface, and a recirculation region in front of the spur dike. Moreover, flow in the wake region consists of a large vertically oriented recirculation region and a smaller laterally oriented recirculation region near the bottom corner downstream of the spur dike. 

KP1.00075: Fluctuating hydrodynamics for curved fluid interfaces: An Extended SaffmanDelbruck approach for driftdiffusion dynamics of particle inclusions Ben J Gross, Paul J Atzberger We develop fluctuating hydrodynamics approaches that extend SaffmanDelbruck theory to capture the collective driftdiffusion dynamics of inclusion particles within curved fluid interfaces. Our extended SD theory and computational methods take into account the two dimensional hydrodynamics of the curved interface coupled with the three dimensional hydrodynamics of the surrounding bulk fluid. Using analytic and computational approaches, we show how Gaussian curvature can significantly impact dissipation within the curved two dimensional membrane fluid to augment the collective driftdiffusion dynamics of particle inclusions. We also present general results on the collective driftdiffusion dynamics when heterogeneous curved structures are present in the membrane geometry showing how these local Gaussian curvature effects influence hydrodynamic coupling in some interesting ways. Lastly we present approaches for computing these hydrodynamic equations on arbitrary compact manifolds, as well as methods for parallelizing our implementation for highperformance computing. We demonstrate our results for applications to dynamics of proteins within curved lipid bilayer membranes and colloidal selfassembly in curved fluid sheets. 

KP1.00076: Experimental Investigation of Downburst Physics to Derive Scaling Laws Jackson Jandreau, Jamey D Jacob The behavior of downbursts and their interaction with the ground and structures is being investigated in order to develop scaling relations. Downbursts are extremely powerful and relatively underexamined phenomena that cause extensive damage to both ground structures and aircraft. Most damage is generally caused by an outburst of descending air upon impact with the ground. Tests are performed in a water tunnel using an elevated cylinder of dense fluid to simulate the highdensity air. The fluid is dropped and its interaction with the ground is observed. Tracer particles in the dense fluid are then analyzed using particle image velocimetry, and observations quantified to develop scaling laws to apply to fullscale downbursts. Conditions analyzed include different combinations of densities and varying amounts of fluid released, as previous tests showed correlation between these factors and the resulting outburst strength. Results are compared against other simulations in order to verify the model’s accuracy. 

KP1.00077: Three Dimensional Modeling of RayleighBenard Stabilization by Forced Domain Oscillation in a Thermally Unstably Stratified System Robert Kunz, Ilker Topcuoglu Recent experiments by our team and others have shown that the onset of RayleighBernard (RB) instability can be delayed by suitable forced oscillation of unstably stratified flow systems. Our recent work includes experimental results obtained in a 4cm x 4cm x 1.5 cm high rectangular air chamber heated from the bottom, and subject to a host of oscillatory vertical motions. We have previously shown that Floquet stability theory predicts the location of the stability boundary in the AmplitudeFrequency plane, at least at the lower frequencies where data was obtained. In this work we solve the discrete weakly compressible (Boussinesq) time dependent NavierStokes (NS) equations in a frame of reference affixed to the test fixture. We are able to predict 2D and 3D stability bounds in very close correspondence to the experimental data and stability theory. We also predict a rich complexity of RB cell topologies in the lowaspect ratio, square cross section domain. 

KP1.00078: Understanding thermal stratification or mixing in liquid metal pools due to penetrating colder jets Brendan Ward, Graham Wilson, Hitesh Bindra High fidelity experimental results are presented for understanding the thermal stratification or mixing in a low Prandtl number (Pr) pool due to the injection of a colder (higher density) jet at the bottom of the pool. While work has already been established for fluids like air and water, research on low Pr fluids (<< 1) (e.g. liquid metals) has fewer experimental data sets. In liquid metals, the higher volumetric thermal expansion enhances buoyant forces, aiding in thermal stratification, while the low Pr extends the thermal boundary layer. To quantify the amount of mixing, the empirical parameter eddy thermal diffusivity (κ_τ) is used. Distinct regimes of mixing efficiency (K = [κ_τ + κ_mol] / κ_mol) are seen: molecular (κ_τ << κ_mol), transitional (κ_τ ≈ κ_mol), & energetic (κ_τ >> κ_mol). Rayleigh and acoustic backscattering techniques are used to generate the high fidelity distributed temperature and flow field data, respectively. The high spatial and temporal resolution of the sensors are required to capture the temperature gradient and fluctuations of temperature and velocity to allow a more complete understanding of stratification or mixing within the pool. 

KP1.00079: Parametric study of inlet conditions for LES of forced plume interacting with a ceiling Ashruf Syed, Amit Kumar Present work concerns LES of forced plume interacting with a ceiling in OpenFOAM. Different inlet types are used for parametric study, starting with a constant inlet velocity & temperature, to using a nonuniform spatially varying profiles from experiment. Velocity, temperature and turbulence quantities are compared at both near and farfield from the inlet for radial profiles, along with axial profiles at different radial locations. Moreover, boundary layer profiles at the ceiling layer are also studied. The turbulent velocities obtained from both the inlettypes are really low in nearfield, with plume remaining intact without any mixing until it hits the ceiling, resulting in an overpredicted vertical velocity along the centreline. To address the issue, a turbulent inlet is adopted which generates artificial fluctuations over the mean velocity profile. These fluctuation scales are calculated based on the maximum/mean values of turbulent velocities from experimental data. This resulted in a proper mixing and entrainment, which increased the turbulence levels near the inlet simultaneously slowing down the plume. Different inlet velocities are considered to check the validity of this concept


KP1.00080: MolecularDynamics Simulation of Sliding Drops Joel de Coninck, Juan Carlos Fernandez Toledano, Laurent Limat We use largescale molecular dynamics (MD) to model drops of liquid sliding across a solid surface under the influence of an external force. The simulations enable us to extract the local, microscopic dynamic contact angle and the velocity of the contactline normal to itself at all points around the drop. Consistent with macroscopic observations, our results confirm that the dynamic contact angle is a function of the local contactline velocity in the normal direction , where is the velocity of the drop’s center of mass and is the slope of the contact line with respect to the direction of travel. We model the velocitydependence of the microscopic contact angle using the molecularkinetic theory, and if slip between the first layer of liquid molecules and the solid surface is accounted for, the contactline frictions recovered are identical with those found in previous MD studies of spreading drops. Moreover, despite the relatively small scale of the simulations, flow within the drop with respect to the solid surface is consistent with that observed in macroscopic experiments. 

KP1.00081: Elliptical footprint drop impact on a solid surface: the role of the impact angle Sungchan Yun Control of drop impact dynamics on solid surfaces has gained a significant attention in a wide range of practical applications, such as surface coating and cooling. Classical drop dynamics is assumed to be axisymmetrical, so symmetry breaking in the dynamics can result in the modified drop hydrodynamics. Drop shaping with an elliptical footprint at the impact moment could alter impact dynamics significantly, leading to antirebound by inducing the extraordinary spreading and retraction dynamics, which was previously studied. Here, we focus on the effect of the impact angle on the dynamics during the elliptical drop impact on nonwetting surfaces. The impact angle plays a crucial role in modifying impact dynamics and suppressing bounce magnitude, which are investigated experimentally and numerically. We determine the rebound/deposition regime for varying impact angles, aspect ratios of the shapes, and Weber numbers. The quantitative analyses of the axial momentum of the horizontal and vertical axes are conducted to interpret the mechanism behind the drop deposition at low impact angles. 

KP1.00082: Sliding of a Droplet on a Microgrooved Surface Manish Kumar, Kirti Sahu, Rajneesh Bhardwaj We characterize nonwetting behavior of a microgrooved surface by measuring the sliding angle of a water droplet on it. The rectangular microgrooves are prepared using photolithography techniques on a silicon wafer by coating SU8 photoresist. A highspeed camera is used to record the motion of the droplet, while the surface is tilted gradually to measure the sliding angle. We vary the pitch of the grooves and study its effect on the sliding angle of the droplet in two configurations: (a) droplet migration along the direction of grooves, and (b) droplet migration in the direction perpendicular to the grooves. In case (b), the advancing contact line attaches and receding contact line detaches with the surface as the droplet migrates downward. In contrast to this behavior, in case (a), no change in the relative position of the advancing and receding contact lines is observed. The sliding angle in case (a) is found to be smaller than that observed in case (b). In both cases, it is found that with the increase of the pitch, the sliding angle decreases due to the increase in the contact angle. A theoretical model for sliding angle is also developed and compared against our experimental results. 

KP1.00083: Gradient Crosslinking of Poly (dimethyl) siloxane and Associated Droplet Wetting Vartika Parihar, Soumen Das, Sunando DasGupta Efficient and facile fabrication of a substrate with elasticity gradient has remained an area of contemporary importance due to its potential in a plethora of biological applications such as adhesion and proliferation of cancerous cells etc. However, the existing methods suffer from the use of sophisticated setup and multiple steps involving costly equipment. In this work, a novel straightforward method has been used to impart a temperature gradient (~ 77°C to 144°C) during crosslinking, resulting in a gradient of Young's modulus (~1.21 MPa to 2.38 MPa). The phenomenon is attributed to the fact that higher temperature stimulates the hydrosilylation reaction at the hotter side leading to extensive crosslinking. However, the colder side, due to slower hydrosilylation, allows a relative slip among the polymer chains and helps to dissipate the stress resulting in the lower value of Young’s modulus. The wetting characterization shows the increasing hydrophobic behavior (103° to 117°) towards the softer side. This is attributed to the increasing deformation of the substrate at the threephase contact line due to elastocapillary interaction. 

KP1.00084: Improving the numerical accuracy of sharp interface treatment of evaporation modeling Ashish Pathak, Mehdi Raessi Earlier attempts at computationally solving evaporation problems relied on using singlefluid formulation. In this formulation, the hydrodynamic equations are solved by treating the liquid and gaseous phases as a single fluid with spatially varying properties. Singlefluid formulation provides several numerical advantages: lower memory usage, faster turnaround times and the ability to easily extend an existing multiphase code to handle evaporation problems. Recent studies, however, have shown that singlefluid formulations smear the jump across the interface in quantities like fluid properties, temperature and velocity. This smearing introduces significant errors if the problem of interest is driven by interfacial gradients, e.g., in Stefan problems. Therefore, newer studies on evaporation are preferring a sharp treatment at the interface, for which several twofluid formulations have been proposed. In the present work, we identify some features that are still lacking in the existing twofluid formulations. We also show how these features can result in improved accuracy and how they can be introduced in an existing sharp interface code. 

KP1.00085: Liquid droplet condensation on a solid surface: A phasefield study. HuaYi Hsu Condensation of liquid from the atmosphere on a solid surface is commonly seen in nature. Liquid condensation is with high potential to be utilized in thermal management, water generation, and desalination. To enhance drop condensation more efficiently, it is crucial to understand the generation dynamics and process. Phase field modeling approach has been commonly used to study the formation of structure/substance by external fields at microscopic length scale. A detailed twodimensional numerical investigation of spinodal decomposition model has been established in this study. Initially, both liquid and vapor phase are randomly coexisted in the computational domain, and a lower temperature is given at the solid surface. It is found the small liquid droplet generated along the curved surface and gradually merged into a coalescence droplet. Using a phasefield model, a preliminary study of droplet condensation has been performed and qualitative agreement with experiment is generally achieved.


KP1.00086: Leidenfrost Engine: Dynamics of rotating disks on turbinelike surfaces Prahsant Agrawal, Gary G. Wells, Glen McHale, Rodrigo Ledesma Aguilar, Khellil Sefiane, Anthony Walton, Adam A. Stokes, Anthony Bouchoux, Jonathan Terry When a liquid droplet is placed on a surface heated to a temperature significantly higher than the liquid’s boiling point, the droplet levitates on a cushion of its own vapor due to the Leidenfrost effect. This vapor layer provides a virtually frictionless motion of liquid droplets (and sublimating solids), which can be directed by asymmetrically texturing the substrate, which forces a preferential vapour flow direction. Here we investigate the rotation of a liquid pool, supporting glass disks, on heated turbinelike asymmetrically textured substrates. The transparent disk allows us to visualise the liquid distribution over the turbine, which informs our assessment of the torque losses and rotation stability of the supported disk. We also demonstrate that by replenishing the liquid, sustained rotation can be achieved. Experimental observations are supported by an analytical model. The dynamic analysis of the rotation of such Leidenfrost liquid (and solid) rotors paves the way for developing mm and submm scale heat engines. The concepts here can be extrapolated to alternative liquid and solids to develop applications in extreme environments where temperature differences are common. 

KP1.00087: Hydrodynamics of Drop Coalescence Md Mahmudur Rahman, Willis Caleen Bailey Lee, Arvind Balakrishnan Iyer, Stuart Joseph Williams Hydrodynamics of drop coalescence has been studied theoretically and numerically by solving Navier Stokes equation considering a single fluid after the first touch. Many experiments documented bridge growth with the use of high speed videography and electrical method. However, internal fluid motion during coalescence has not been extensively studied, in part due to the spherical shape of the drop. Here we observed overall fluid motion (except at the site of early coalescence) using particle image velocimetry for 2D coalescence. We observed that fluid motion inside the bulk drops are inertial and governing fluid flow in the bridge region is one dimensional. At the merging interface, incoming liquids join and coflow in the perpendicular direction. We extended our observation to 3D coalescence and formulated a new scaling law encompassing all viscous liquids. We validated scaling argument at early stage of coalescence through experimentation. Finally, we conclude that while flow in the bulk drops is inertial, the dominant resistance comes through viscous effect in the merging interface region and at the lesser extent in the bridge region. Early dynamics of drop coalescence was dominated by viscous flow and possible crossover from viscous to inertial depends on the Ohnesorge number. 

KP1.00088: Even Hot Water Droplets Can Bounce off of a Superhydrophobic Surface Armela Murrizi, Samira Shiri, James C Bird Drops of scalding water can cause severe burns when it sticks to skin or clothing. One proposed method to mitigate this problem is to develop a superhydrophobiccoated fabric which would minimize the contact time of the hot drop, and by extension the heat transfer. Yet, drops that bounce on a superhydrophobic surface when they are warm can stick to the surface if they approach boiling temperatures. These results are consistent with the idea that evaporated vapor from the drop that condenses on the solid would transition the drop into a Wenzel state. This circumstance provides a new challenge to identify if a material or surface coating exists that could overcome this limitation. Here, we compare several distinct superhydrophobic surfaces and find that there indeed exists some structures that can repel water even at near boiling temperatures. We explore various parameters for each of the surfaces that might shed insight into why only certain surfaces can overcome the nearboiling bouncing limitation. 

KP1.00089: Effect of Microstructure on Liquid Infused Surfaces during Condensation Phase Change Daniel Orejon, Yota Maeda, Fengyong Lv, Peng Zhang, Yasuyuki Takata Liquid infused surfaces (LIS) have received increasing attention for their extremely low contact angle hysteresis and excellent droplet mobility, which makes them potential candidates for antiicing and heat transfer purposes. The excellent low adhesion of LISs is owed to the presence of a lubricant/oil that decreases further the intimate direct interactions between the solid surface ant the condensate. Although the effect of micropillar structure on droplet mobility after sessile drop deposition has been extensively addressed, the presence or absence of microstructures during dynamic condensation has not been reported up to date. Two different micro/nanostructured LISs and two nanostructured LIS were fabricated following facilescalable etching and oxidation techniques. The density and size of the microstructures was found to differ depending on the etching time. All four LISs were subjected to condensation on an environmental chamber. Here, ewwe present first experimental evidences and surface energy analysis to demonstrate and support the greater shedding velocities and condensation performance of micro/nanostructured LISs when compared to solely nanostructured LISs. 

KP1.00090: Wettability of a Vibrating Surface Nicolas CandiaMuñoz, Luis GaeteGarretón, Yolanda VargasHernández, Josue MenesesDíaz 

KP1.00091: Abstract Withdrawn
Droplet starts spreading over a surface right after its initial contact. In recent years, researchers have mainly examined the initial spreading of droplet (V_{D}∼0 m/s) over horizontal surfaces. However, spreading may take place on surfaces with different inclination angles. Our objective for this project is to understand how early stages of droplet spreading takes place on an inclined surface compared to a horizontal surface i.e. if different spreading law (r∼t;t^{1/2} or t^{1/10}) are obeyed. Therefore, experimental setup has been designed with surfaces having different wettabilities and different angle of inclination to observe the spreading behavior. Images were taken at 40,000 fps from bottom and side view to understand, if gravity plays a role at the initial stage of spreading. Our preliminary analysis for three different inclined angles suggests that neither wettability nor gravity seem to play a role at the initial stages of spreading, hence a circular spreading is seen; therefore, one can consider the initial spreading similar to a horizontal surface i.e. it follows r∼t^{1/2} . 

KP1.00092: Electrokinetic instability in coflowing fluids with matched conductivities Le Song, Purva Jagdale, Liandong Yu, Xiangchun Xuan Electrokinetic fluid flows with conductivity gradients have been reported to generate instability waves if the applied electric field reaches a threshold value. We demonstrate in this work that such electrokinetic instabilities can also be formed at the interface of ferrofluid and buffer solutions with matched electric conductivities. We develop a twodimensional numerical model to potentially explain this phenomenon. It is found that the permittivity difference between the two fluids is not the primary cause of the observed electrokinetic instability. We therefore propose to use the diffusioninduced conductivity gradients that are formed at the ferrofluid/buffer interface because of the mismatched diffusivities of ferrofluid nanoparticles and buffer ions. However, due to the limitation of a twodimensional model, our predicted threshold electric fields are much smaller than the experimental values. 

KP1.00093: Experimental, numerical and analytical investigation of electrohydrodynamic flow in pointtoring corona discharge Igor Novosselov, Yifei Guan, Ravi Sankar Vaddi, Alberto Aliseda An electrohydrodynamic (EHD) flow in a pointtoring corona configuration is investigated experimentally and via multiphysics mathematical and computational model. The mathematical model couples the ion transport equation and the NavierStokes equations (NSE) to solve for the spatial distribution of electric field, flow field, and charge density. The numerical model includes temporal resolution and charge diffusion. Modeling results are validated against experimental measurements of the cathode voltage, ion concentration, and velocity profiles. The maximum flow velocity is at the centerline, and it decays rapidly with radial distance due to the viscous and electric forces acting on the partiallyionized gas. To understand this coupling, a nondimensional parameter, X, is formulated as the ratio of the local electric force to the inertial term in the NSE. The approach allows the model to be used for the entire EHD domain, providing insights into the nearfield flow in the corona region. 

KP1.00094: Experimental study of ACdriven flow through nanopores with singleside conductive coatings Cindy Harnett, Mohammad Islam, Jasmin Beharic Electroosmosis can turn a nanoporous material into a direct current (DC) driven fluid pump with no moving parts. When the pumps are used to drive aqueous flow, electrolysis gases must be vented. Alternating current (AC) approaches including induced charge electroosmosis (ICEO) and AC electroosmosis (ACEO) use surface charges on asymmetric conductive films to rectify flows, avoiding the electrolysis problem. However, most designs demand metal features on the nonplanar surfaces of microfluidic channel walls, making it challenging to create nanoscale channels that can hold off back pressures comparable to insulatorbased DC electrokinetic pumps. A throughsubstrate format makes different fabrication methods available including those from the domain of nanoporous membranes. Our results show that a nanoporous membrane with a metal coating on one side, placed in an AC electric field, can drive throughflows and create pressures up to 400 Pa. The pores are in the 200800 nm diameter range, significantly larger than asymmetric conical nanopore pumps, and operate by a different mechanism. Largerscale variants of the device filled with tracer particles show vortices resembling those in previous ICEO/ACEO devices. 

KP1.00095: Investigation of Electrokinetic Ion Transport in SelfAssembled Graphene Oxide Nanochannels RueyJen Yang, ChihChang Chang, DaoMing Chang This study investigates a twodimensional material  graphene oxide (GO), identifies the structure of the GO nanochannels, and focuses on the analysis of ionized electrokinetic transport in the nanochannels. We begin with the discussion on the dissociated functional groups about the GO. In conjunction with the number of dissociated functional groups and the electric double layer theory, surface charge density and the distribution of ions in the GO nanochannels can be obtained. Second, we proposed a selfassembled GO nanochannel. We controlled the height of the nanochannels during fabrication and measured the conductance of the nanochannels under different concentrations of potassium chloride aqueous solution and hydrochloric acid. We inferred that proton hopping benefits from the organized hydrogenbond network due to the presence of structured water and functional groups, yielding higher proton mobility in the GO nanochannels. Slipenhanced conductance from electrosmosis in the GO nanochannels becomes significant at high surface charge density. Through this study, the behavior of fluids in the GO nanochannels can be more clearly revealed. 

KP1.00096: "Hutang untuk NUTFAH" for "Debt for Nature Swap" Denotes Widastra Hidajatullah, Widastra Hidajatullah Inbetween letter to HE. Mr. Ir. Silmy Karim,ScD dated May 23,2017 about "Hutang untuk Nutfah" lied abstracts "Price Theory & Econophysics" as well as "UFOs between Calectro & Electroceramic " dated 19/25 May 17 each. Accompanies backlog of "Best Minister in the World 2018" to Her Majesteit Mvr Dr Hj SRI MULYANI INDRAWATI awarded herewith 6characters permutation from US 2013/0234070 A1 to <234070.pdf> description of Debt for Nature Swap.Accomplishes "multiplications" also meant "times" offered Ten Million Multiplication originated from Ten Million kron Prizes of NOBEL Prizes e.g from A. Fert & P. Gruenberg as Nobrl Prize in Physics Winners 2007 under 1982June pay s[S]cale [Syntax of ] Relativi[zation]ty. Further, suggested Creative Commons Attribution 4.0 International from <commsphys@nature.com> to bunchs the Surat Keterangan no 1387/UN2.F3.D/PDP.00.07.01 Ijazah/2016 signed by Prof Dr. Bambang Wibawarta,SSMA dated July 14, 16 as Certificate of Payments.Ever quoted whereas for times t >∞ so Debt/Gross National Product also >∞ and it followed Johannes&Budiono Sri Handoko:"Matematika untuk Ekonomi" will "Menyulitkan Negara"


KP1.00097: The Saturated and Supercritical Stirling Cycle Thermodynamic Heat Engine Cycle Matthew David Marko On the assumption that experimentally validated tabulated thermodynamic properties of saturated fluids published by the National Institute of Standards and Technology are accurate, a theoretical thermodynamic cycle can be demonstrated that produces a netnegative entropy generation to the universe. The experimental data on the internal energy can also be used to obtain a simple, empirical equation for the change in internal energy of a real fluid undergoing isothermal expansion and compression. This demonstration provides experimental evidence to the theory that temperaturedependent intermolecular attractive forces can be an entropic force that can enhance the thermodynamic efficiency of a realfluid macroscopic heat engine to exceed that of the Carnot efficiency. A practical modification of the Stirling thermodynamic heat engine cycle will be presented. This engine uses supercritical argon gas to take advantage of the attractive intermolecular forces of the working fluid to assist in compressing the working fluid, increasing the overall heat engine efficiency.


KP1.00098: Transient State Power Analysis of HeavyDuty Diesel Engine Spencer Hall, Joshua Bittle, Avery Pendley, James Cook, Mason Moore, Allen Parker Vehicles with internal combustion engines, almost exclusively operate in transient state, which occurs when the torque or speed of the engine varies. Those variations occur when conditions like speed, load, or incline of the road change. This research analyzes the energy gains and losses through different pathways – fueling, shaft work, radiator, and exhaust  during transient operation. This test was conducted using a twentyminute HeavyDuty Engine drive cycle. The results show a general trend, that when the engine begins producing more shaft power, the proportion of energy lost to the radiator drops and then, increases as the engine decreases in power. At high loads, the energy lost through exhaust decreases, leaving shaft work to be the largest percent of energy output. However, the data tends to show that at low loads or idle, both the energy loss at the radiator and exhaust become larger than the shaft work, which indicates lower operating efficiency. This preliminary work developing the capability to analyze the engine performance under transient conditions will serve as a starting point for future work to investigate how to improve the transient performance. 

KP1.00099: Multiscale Modeling of Ignition Damkohler Number Effect on Cool Flame Propagation at Elevated Temperature and Pressure Using nHeptane/Air Mixture Tianhan Zhang, Yiguang Ju Laminar cool flame propagation speed at elevated temperature and pressure is fundamentally important in many research areas such as knocking control in advanced engines, and it provides one of the most important reference numbers to characterize and model combustion process. However, the laminar cool flame speed especially at high ignition Damkohler number is a challenging task since it is no more the classical eigenvalue problem and need to be reconsidered. The current study proposed a new numerical method to measure cool flame speed at elevated temperature and pressure with a wide range of ignition Damkohler number. The primary focus of the current study is on the effects of pressure, temperature, equivalence ratio and ignition Damkohler number. The results show that the laminar cool flame speed increases with temperature before and after the negative temperature coefficient(NTC) region. While inside NTC region, the laminar cool flame speeds decreases with higher temperature due to the inhibited low temperature chemistry. In addition, the peak laminar cool flame speed increases with the pressure due to the crossover temperature change. 

KP1.00100: Experimental study on the tidal current and pumped storage hybrid power generation Jihoon Kim, Patar Ebenezer Sitorus, Bo Reum Won, Jin Hwan Ko Recently, tidal current energy has been considered as a good candidate for the alternative energy source to reduce our dependency on fossil fuels. The present research project is aimed to develop a tidal current and pumped storage hybrid power generation system, which is combined with the dual ﬂapping type system as the tidal current generator. In the hybrid concept, the ﬂapping type tidal current generator in the changed power transmission of vertical arrangement can be applied to pump seawater through its mechanical power, which becomes a new concept in hybrid power generations. Through an experimental study and its parametric analysis conducted while varying design factors, a high pitch angle and a high arm angle were found to be advantageous. In the future, the design of a realscale prototype with the tidal current and pumped storage hybrid power generation system will be realized based on present results. 

KP1.00101: Measurements of Planar Density Gradients using Structured LightField Focusing Jonathan Eliel Reyes, Kareem Ahmed Typical diagnostic techniques like schlieren and shadowgraph are line of sight measurements, as in they provide an integral of the 3D refractive disturbances projected on a 2D plane. An advanced structured lightfield focusing optical diagnostic technique is developed for flow field measurements of planar density gradients. The innovative method is based on using lightfield physics and multiple light sources to generate twodimensional planar focused imaging. Unlike a plenoptic camera that captures the spatial distribution of the 4D lightfield, the proposed diagnostic technique structures the light to generate a single plane of focus that is acquired with a traditional camera, i.e., inverse plenoptic. The technique is further unique in that it provides velocity fields from particles at extreme sampling rates (>15kHz) driven by the forward scatter relative to traditional particle image velocimetry (PIV) systems. The diagnostic system setup and model will be presented. The technique is demonstrated on various flows including imaging of supersonic jets, spray imaging and velocimetry at high acquisition rates to characterize the performance of the diagnostic system. 

KP1.00102: Volumetric PTV Measurements of Flow Around and Within a Model of Gale Crater Gianluca Blois, Nathaniel Bristow, Aaron Boomsma, Dan Troolin, Wing T Lai, Kenneth Christensen Impact craters on the surface of Mars record the history of the geological processes which shape the surface of the planet. The central mound within Gale Crater is thought to be formed by aeolian weathering, and it has been hypothesized that secondary flow structures within the crater are responsible for the longterm evolution of the morphology of the crater as a whole. Here we experimentally study the flow structure within the crater through fully threedimensional velocity measurements in a refractive index matching (RIM) flow facility. The refractive index of a castacrylic model of Gale Crater is matched with an aqueous solution of Sodium Iodide, allowing full optical access to the recessed region of the crater. This region of the flow is critical to understanding the flow physics driving the geological evolution of the crater and the formation of the mound in its center. The results presented herein are obtained using TSI’s V3V system which utilizes a volumetric particle tracking approach to yield high resolution 3D vector fields. This talk will highlight increased yield and accuracy of the PTV results and associated statistics using a 3D particle reconstruction method based on a multiple particle identification approach. 

KP1.00103: Motion Estimation under Location Uncertainty for Turbulent Fluid Flows Shengze Cai, Etienne Mémin, Pierre Dérian, Chao Xu We propose a novel optical flow formulation for estimating 2D velocity fields from images depicting the evolution of a passive scalar transported by a fluid flow. This motion estimator relies on a stochastic representation of the flow allowing to incorporate a notion of motion uncertainty. In this context, the Eulerian fluid flow velocity field is decomposed into two components: a largescale motion field and a smallscale uncertainty component. We define the latter as a random field. Subsequently, the data term of the optical flow formulation is based on a stochastic transport equation derived from location uncertainty principle. In addition, a specific regularization term built from the assumption of constant kinetic energy involves the same diffusion tensor as the one appearing in the data term. Opposite to the classical estimators, this enables us to devise an optical flow method dedicated to fluid flows with a clear physical interpretation. Experimental evaluations are presented on both synthetic and real world image sequences. Results and comparisons indicate good performance of the proposed formulation for turbulent flow motion estimation. 

KP1.00104: Dense Motion Estimation of Particle Images via a Convolutional Neural Network Chao Xu, Shengze Cai, Shichao Zhou In this work, we propose a supervised learning strategy to the fluid motion estimation problem (i.e., extracting the velocity fields from particle images). The purpose of this work is to design a convolutional neural network (CNN) for estimating dense motion field for particle image velocimetry (PIV) which allows to improve the computational efficiency without reducing the accuracy. Firstly, the network model is developed based on FlowNet, which is recently proposed for endtoend optical flow estimation in the computer vision community. The input of the network is a particle image pair and the output is a velocity field with displacement vectors at every pixel. Secondly, in order to train the CNN model, a synthetic dataset of fluid flow images is generated. To our knowledge, this is the first time to use a CNN as a global motion estimator for particle image velocimetry. 

KP1.00105: Azimuthal forcing of an axisymmetrically oscillating selfexcited jet Wai Kong Liu, Yuanhang Zhu, David D.W. Ren, Abhijit Kumar Kushwaha, Larry K.B. Li At a sufficiently low density, an open jet flow can become globally unstable, transitioning from a steady state to a selfexcited state characterized by axisymmetric oscillations at a discrete natural frequency. However, if such a flow is then forced sufficiently strongly at a different frequency, it can oscillate at that frequency instead, leaving no evidence of the original natural mode. In lowdensity jets, this forced synchronization process has been explored for longitudinal forcing, but relatively little is known about how such jets respond to azimuthal forcing. In this experimental study, we examine the effect of azimuthal forcing on a selfexcited lowdensity jet, with the aim of characterizing the bifurcations and nonlinear dynamics leading up to complete synchronization. We force the jet acoustically over a wide range of frequencies and amplitudes, and measure its unsteady response using hotwire anemometry and highspeed Schlieren imaging. The results should offer new insight into the way selfexcited axisymmetric hydrodynamic modes respond to external azimuthal acoustic forcing. 

KP1.00106: Decay of a mesoscale oceanic eddy: analysis of linear stability dynamics and critical levels Yun Chang, MaryLouise Timmermans This study addresses the linear stability of an oceanic mesoscale eddy. A linear stability analysis of the quasigeostrophic potential vorticity equation governing an idealized Gaussian vortex in a continuous stratification is performed, and the properties of the instability are analyzed. We show how growth of the instability is via mutual amplification of waves at different levels in the eddy, analogous to the Eady baroclinic instability. The fastest growing mode gives rise to enhanced vertical and horizontal density gradients that coincide with the critical level in the vicinity of the perturbed eddy; at this level, the mean angular speed is equal to the angular phase speed of the perturbation. We show how these enhanced density gradients relate to maximal radial water parcel displacement at the critical level. Results shed light on the physics of mesoscale eddy decay and further demonstrate the role of enhanced mixing at critical levels in the ocean. 

KP1.00107: RayleighBenard instability in the presence of inhomogeneous flow Y. Huang, S. Sen, B. Yang We will report our studies on the effect of shear flow in stabilizing interchange mode. Hydrodynamic RayleighBenard instability, as a prototype due to its simplicity but similar physics to interchange, will be studied. Both the effect of flow shear and flow curvature will be studied and the consequent effects in fluid and plasma dynamics will be reported. 

KP1.00108: Modulation on turbulent puffs in pipe flows by dilute dispersed microbubbles Kotaro Nakamura, Yuji Tasaka, Yuichi Murai We examined mutual interactions between a turbulent puff and microbubbles, where the maximum volume fraction is less than 0.018%, in a horizontal pipe flow at Re = 1,900. Forty trials to investigate flow status were performed at different perturbation amplitudes for both of singlephase and flows with the bubbles. The results indicated that adding bubbles enhances puff creation. The enhancement may be due to increases of local volume fraction. A tiny amount of bubbles is accumulated in vortical structures embedded in a puff, and the accumulated bubbles may reduce the area of the core, which leads to enhancing the vortices. To estimate the accumulation numerically, bubble motions in a puff were calculated by EulerLagrange simulations. Motion equations for spherical bubbles were solved by a oneway simulation, which was coupled with velocity fields of a puff obtained by DNS. Using a box counting method for bubbles, we confirmed that bubbles are accumulated in a puff. For indicating that bubble distributions in a puff can be modified relative to in laminar flows experimentally, the distributions are visualized using laser sheet and quantified by image processing. 

KP1.00109: Linear asymptotic phase of the contact surface ripple growth in RichtmyerMeshkovlike flows Francisco CobosCampos, Juan Gustavo Wouchuk, Takayoshi Sano The RichtmyerMeshkov Instability develops when a planar shock collides with a corrugated interface between two fluids. A shock is transmitted and a shock or rarefaction is reflected back. Due to front waves corrugation, hydrodynamic perturbations are generated in the compressed/expanded fluids which drive the Interface Ripple Growth (IRG) in time. When wave fronts are far away and regain planar shape (in ideal gases), no more pressure perturbations exist inside the bulks. The linear IRG has two phases: a transient compressible phase in which oscillations due to sound waves are noticed; and, a linear incompressible phase when IRG reaches its asymptotic velocity. For this period, a temporal law of the form: ψ_{i} (t) = _{ }ψ_{∞} + u_{i}^{ }t, where u_{i} is the growth rate, and ψ_{∞} is an asymptotic ordinate to the origin [1,2]. A comparison with experiments and simulations has been done showing a very good agreement between theory and experiments/simulations done in a wide range of regimes for the cases in which the initial ripple amplitude is small enough [1,2]. In this work, a study of the linear IRG is presented. Besides, it is shown that u_{i} and ψ_{∞} are useful quantities for incompressible models in order to take into account compressibility effects occur during the transient phase. 

KP1.00110: Flow instability in a plane sudden expansion followed by a curved duct Lyes Khezzar, Abdelkader Filali, Omar K Matar Instabilities detection and characterization for a laminar flow of an incompressible fluid through a twodimensional plane sudden expansion followed by a curved duct, is carried out numerically using a finitevolume method. The objective of the present study is to characterize the first critical Reynolds number Re_{c1 }in which a third recirculation zone appears and the second critical number Re_{c2 }in which the flow becomes unstable with periodic oscillations of the flow variables. The results indicate that instabilities occur for the different sudden expansion aspect ratios, AR, investigated including AR = 1/2, 1/3 and 1/4, at different critical Reynolds numbers Re_{c2 }and that the curved pipe with AR = 1/4 is the more sensitive geometrical model that produces instabilities at lowest critical Re_{c2 }number. The flow field for different sudden aspect ratios, critical Re numbers, and the mechanisms responsible for the appearance of these instabilities are presented and discussed in detail. 

KP1.00111: Fluid Mechanics and the Bible as Explained by the Philosophy of Deific Naturalism in Christian Science Amy Lang “Science has to have a metaphysical framework to operate with confidence. Only then can it claim a truth that all should respect.”(Beyond Matter, Trigg, p.146) The current view of naturalism, which assumes all cause as physical and omits any spiritual cause (God), cannot explain why there is order in the universe. Fluid mechanics demonstrates this order (e.g. exact viscous flow solutions perfectly predict laminar flow measurements). A potential scientific revolution which designates metaphysical principles for the construct of reality requires a paradigm shift from a basis of matter to mind. Planck was one of many physicists who proposed that matter is in fact formed by consciousness. Christian Science, as stated by Mary Baker Eddy in her book Science & Health, fits such a paradigm. Her discovery explains the physical realm as being influenced by two sources of consciousness: mortal mind which constructs the subjective state of matter, and the divine Mind as the only eternally good cause and creator. She defined deific naturalism as the natural and all pervasive cause of God bringing principled order to the physical realm. The metaphysical method of prayer applies this spiritual cause, restoring health and order, and scientifically explains Biblical fluid mechanic anomalies. 

KP1.00112: Investigation of measurement characteristics of different types of Anemometers Masafumi Yamazaki, Shigeo Kimura When crosswinds are too strong, it is necessary to refrain from operating trains and trucks in order to avoid accidents. Since the wind direction and the wind speeds are the two important indicators of the danger, anemometers are installed in various places from urban to mountainous areas. The wind speed is greatly influenced by the surrounding environment, thus Japanese Meteorological Agency recommends that the anemometer should be set sufficiently far from buildings and installed at the top of the column. However, depending on the conditions of the installation site, sometimes it is inevitable to attach the anemometer to a support extended in the horizontal direction from the middle of the column. In that case, the measurement value is disturbed when the wind comes from the direction of the column. In order to investigate the influence of the support on the measurement, the wind speeds up to 20 m/s were measured with several anemometers which adopt different measurement methods such as cup and ultrasonic. 

KP1.00113: Visualization of the flow induced by a rotating disk in a cylindrical container Hiroki Kurakata, Jun Sakakibara The flow induced by a rotating disk in a cylindrical container has been applied in a wide variety of rotating machineries. This flow is affected by Reynolds number Re=R^{2}Ω/ν and the aspect ratio of the cavity that consisted of a rotating disk and a cylindrical container h/R, where R is the radius of the disk and Ω is the angular velocity, ν is the kinematic viscosity of the working fluid, h is the height of the cavity. We visualized this flow with flake particles and measured velocity by 3D particle tracking velocimetry (3DPTV). In this study, we investigated the features of this flow at low Reynolds number such that turbulent transition would occur. Comparison of the visualized flow patterns during turbulent transition with the transition diagram of Schouveiler et al.(2001) [J. Fluid Mech., vol.443, pp.329350] will be presented. 

KP1.00114: Aggregation Plithogenic Operators in Physical Fields Florentin Smarandache The plithogenic aggregation operators (intersection, union, complement, inclusion, equality) are based on contradiction degrees between each element's attributes’ values, and the first two are linear combinations of the fuzzy operators’ t_{norm} and t_{conorm}. Their applications are presented in this paper.


KP1.00115: Inferring compressible fluid dynamics from vent discharges during volcanic eruptions Joshua Mendez, Corrado Cimarelli, Josef Dufek, Damien Gaudin, Ronald Thomas Observations at numerous volcanoes reveal that eruptions are often accompanied by continual radio frequency (CRF) emissions. The source of this radiation, however, has remained elusive until now. Through experiments and the analysis of field data, we show that CRF originates from proximal discharges driven by the compressible fluid dynamics associated with individual volcanic explosions. Blasts produce flows that expand supersonically, generating regions of weakened dielectric strength in close proximity to the vent. As erupted material—charged through fragmentation, friction, or other electrification process—transits through such a region, pyroclasts remove charge from their surfaces in the form of small interparticle spark discharges or corona discharge. Discharge is maintained as long as overpressured conditions at the vent remain. Beyond describing the mechanism underlying CRF, we demonstrate that the magnitude of the overpressure at the vent as well as the structure of the supersonic jet can be inferred in real time by detecting and locating CRF sources. 

KP1.00116: On the differential torque exerted on double concentric boundaries by inbetween thermal convection Tomoaki Itano, Taishi Inagaki, Naoto Yokoyama, Masako SugiharaSeki The modern seismic tomography measurements have elucidated that, lubricated by the liquid outercore, the solid innercore rotates slightly faster than the rest solid parts, the mantle and crust. The fluid motion in the outercore, which is still veiled for us, possibly asymmetric with respect to east/westward circulations via the Coriolis effect, so that outercore thermal convection may propagate to pro/retrograde directions, which was pointed out by Kimura et al [Phys. Fluids 23 074101 (2011)]. Here, we revisit a speculation on whether thermal convection induced between double concentric axisymmetric boundaries could allow them to permanently rotate with a difference in rotation rate. We consider a simple system of double concentric cylindrical boundaries freely rotating around their axis and Boussinesq fluid confined between them, which are initially corotating at an identical rotation rate. We argue a possibility that thermal convection generated with an increase of the difference in temperature of the boundaries produce a small difference in magnitude of the net tangential stress on the boundaries. 

KP1.00117: Ray systems in granular cratering Tapan Sabuwala, Christian Butcher, William Powell, Gustavo Gioia, Pinaki Chakraborty In classical experiments of granular cratering, a ball dropped on an evenedout bed of grains ends up within a crater surrounded by a uniform blanket of ejecta. We show that that uniform blanket of ejecta changes to a ray system, or set of radial streaks of ejecta, where the surface of the granular bed includes undulations, a factor that has not been addressed to date. By carrying out numerous experiments and computational simulations thereof, we ascertain that the number of rays in a ray system $\propto D/\lambda$, where $D$ is the diameter of the ball and $\lambda$ is the wavelength of the undulations. Further, we show that the ejecta in a ray system originates from valleys located in a narrow annulus of diameter $D$ with center at the site of impact. The impacting ball creates a hemispherical shockwave, whose interaction with the surficial valleys engenders the ray system. Our findings may help shed light on the enigmatic ray systems that ring many impact craters on the Moon and other planetary bodies. 

KP1.00118: Mesoscopic Modeling in Organic Spintronics, Optical Engine & Quantum Optics to NonLaser Fusion Widastra Hidajatullah "Electron exchange & electron or phototriggered electron exchange which are two central topics in related fields of molecular magnetism & molecular spintronics through control of external (optical. redox and/or magnetic ) properties in a use of several physics (spectroscopy, magnetic, electrochemical and/or photochemical )Maria Castellano Sanz2013. Obey analytical studies of common mechanism previously named "spinterface" have been forecast through mesoscopic physics of electrons & photons from Ackerman & Gilles Montambaux e.g. the ability to control spin polarization coincides with electromechanical coupling effect between electric polarization & mechanical strain gradient [ to mechanical disturbances whose propagatesHF Olster:"Musics Physics & Engineering"1967 ] 

KP1.00119: 3DPTV study of flow inside the vacuum cleaner head Hisataka Ban, Ryotaro Iguchi, Jun Sakakibara While vacuum cleaners with a motorized brush inside cleaner head are widely used, the influence of the brushes on dust collection performance has not been clarified. For this purpose, it is necessary to examine a flow inside a cleaner head. In this study, we measured the velocity distribution inside the commercial cleaner head with the _{}rotating brush. The mean velocity field inside the head was captured by 3DPTV. In the absence of the brush, the existence of reverse flow away from the suction port was observed. The flow heading to the suction port along the inner wall surface could be confirmed. With the stationary brush, the reverse flow was suppressed. While the fast flow near the floor surface was passing through the bristles of the brush, the fluids distant from the floor moved along them. Also the formation of the vortices between the bristles was observed. With the rotating brush, the deceleration due to collision with bristles was slightly reduced, so the flow was heading to suction port without forming the vortices. Also the flow along the inner wall surface was similar to the case without the brush. 

KP1.00120: Effect of Volume Fraction on Droplet Breakup in a Concentrated Emulsion Alison Dana Bick, Jian Wei Khor, Sindy K.Y. Tang In droplet microfluidics, microdroplets are used as biochemical reactors. In contrast to solid wells, drops are metastable and prone to breakup, which compromises the accuracy and throughput of the assay. Unlike single drops, the breakup process in a concentrated emulsion is stochastic. We examine the stability of a concentrated emulsion during its flow in a tapered microchannel consisting of a narrow constriction, a geometry commonly used for the interrogation of droplet content. Analysis of the behavior of a large number of drops (N~ 5000) shows that the probability of breakup increases with increasing drop packing (i.e. volume fraction). There also exists a critical volume fraction below which drop breakup probability reduces to zero. This work represents an important step towards understanding the interactions among the drops governing instability in concentrated emulsions. 

KP1.00121: Predicting Drop Arrival Sequence Based on Starting Position Alison Dana Bick, Ya Gai, Sindy K.Y. Tang In droplet microfluidics, microdroplets are used as biochemical reactors. Each of these droplet reactors can contain different reactions. Predicting drop sequence as they flow in a microfluidic system is important for tracking the content of the drops. We find that at low capillary numbers, when up to 4 rows of concentrated emulsion flow together and converge into a single channel, the order that these drops enter the constriction can be predicted. Furthermore, the drops’ arrival sequence can be predicted based on their starting position in the straight channel. We demonstrate the robustness of the system by showing that the drop order sequence can recover from small defects in the emulsion. Practically, our results enable drop tracking based on drop starting position rather than chemical labeling, and can lead to significant cost reduction in droplet assays. 

KP1.00122: Dynamics of the piezoelectric driven ink jetting DuckGyu Lee, Eunjoong Lee, Kyungjun Song, Shin Hur We study the dynamic behavior of inks extracted from piezoelectric inkjet printheads. It is known that ink droplets are ejected from a nozzle when an acoustic wave generated by a piezoelectric film that vibrates applies a sufficient pressure to the ink. This behavior is determined by the size and shape of the ink channel as well as the waveform of the voltage applied to the piezoelectric film. We used commercial software COMSOL to investigate the effect of chamber geometry parameters on the dynamic behavior of ink jet. First, we looked at how acoustic waves propagate through the ink channels for different sized structures. We then observed the change in sound pressure at the nozzle for each case. Finally, we found a condition that caused ink injection. Based on this work, we suggest a design rule of a inkjet print head for a given inkjet speed and volume. 

KP1.00123: Osmotic Pressure Characterization of Ionic Liquid inside Polymersomes Eunseo Kim, Hyomin Lee, In Seok Kang Polymersomes possess great potential as a carrier due to enhanced stability compared to liposomes, and their structure which resembles natural biomembrane system, enabling controlled release by osmolarity difference across the semipermeable membrane. Moreover, incorporating ionic liquid as the internal fluid in a polymersome allows additional functionalities including solubilization of poorly soluble drugs, antimicrobial properties, and enhanced thermal stability. In this work, polymersomes with ionic liquid interiors dispersed in an aqueous phase were fabricated and osmotic pressure of the ionic liquid interior was investigated. The membrane permeability of the vesicles, as well as the osmotic pressure of the inner ionic liquid, was determined by monitoring the polymersomes’ response to an osmotic gradient. By simultaneously performing mean field lattice model analysis, we observe that the experimental value of osmotic pressure in ionic liquids deviates from the classical van't Hoff's Law. This is likely due to the steric effects of ions. We anticipate that the results of this study will be useful for drug delivery and nanoreactor applications involving ionic liquids. 

KP1.00124: Efficient propulsion and hovering of bubbledriven hollow micromotors underneath an airliquid interface Xu Zheng, Haihang Cui The autonomous motion of artificial micromotors has attracted great attention recently owing to their applications in biomedical and environmental areas. In this study, we develop a new type of hollow selfmotile Janus micromotor that moves just underneath the airliquid interface driven by microbubble cavitation. It is the first time to our best knowledge to report the propulsion mechanism of the cavitationinducedjetting for micromotor. In contrast to previous studies that only focused on the direct momentum exchange between a Janus micromotor and microbubbles, we unveil the significant contribution of the hydrodynamic effect during the bubble collapse stage. Four different modes of propulsion are identified by quantifying the dependence of propulsion strength on microbubble size. Different from common solid Janus micromotors, our hollow micromotors manifest instinct propulsion behavior underneath the airliquid interface. In particular, the mechanism of the vertical dynamic hovering can keep a microobject whose density is lower than water moving beneath the airliquid interface. We show that the cavitationinduced jetting better utilizes the energy stored in the bubble to propel the micromotor, and thus enhances the energy conversion efficiency by three orders of magnitude. 

KP1.00125: Particle focusing and separation in xanthan gum solutions Di Li, Xiangchun Xuan The passive manipulation of particles in viscoelastic fluids has received an increasing interest in the microfluidics community for the past decade. It exploits the flowinduced elastic lift and as well inertial lift (if the Reynolds number is not small) to focus particles toward size and shapedependent equilibrium positions. Such a continuous separation has thus far been demonstrated in viscoelastic fluids with a negligible or weak shearthinning effect. We present in this work a systematic experimental study of the fluid shearthinning effect on particle focusing and separation in weakly elastic xanthan gum solutions through straight rectangular microchannels. The effects of xanthan gum concentration and channel depth are examined for particle focusing and separation under varying flow rates. 

KP1.00126: Crossstream inertial migration of rigid microparticles in microchannels with powerlaw fluid Fatima Ezahra Chrit, Alexander Alexeev Separation and focusing of cells are critical processes in biomedical applications. In these applications, the samples of interest composed of populations of cells with different sizes, shapes, and properties need to be separated for further analysis. Commercially available sorting techniques are complex and require high cost procedures to label cells. Researchers focus on the development of labelfree strategies for sorting that rely on the intrinsic properties of the cells. One of the approaches to achieve sizebased separation of biological and synthetic particles is based on the inertial crossstream migration of particles within microchannels with a pressure driven flow. In this study, we use computational modeling based on LatticeBoltzmann method to probe crossstream migration of microparticles in a microchannel filled with a powerlaw fluid. We show that the inertial particle separation can be significantly enhanced in shear thinning fluids. 

KP1.00127: Numerical Modeling of Surface and Volumetric Cooling using Optimal T and Yshaped Flow Channels Srinivas Kosaraju The layout of T and Vshaped flow channel networks on a surface can be optimized for minimum pressure drop and pumping power. The results of the optimization are in the form of geometric parameters such as length and diameter ratios of the stem and branch sections. While these flow channels are optimized for minimum pressure drop, they can also be used for surface and volumetric cooling applications such as heat exchangers, HVAC and electronics cooling, where minimizing the energy consumption is extremely important. In this research, an effort has been made to study the heat transfer characteristics of multiple T and Yshaped flow channel configurations using numerical simulations. All configurations are subjected to same input parameters and heat generation constraints. Results are validated using comparisons made with similar results published in literature. 

KP1.00128: Fluid rheological effects on electroosmotic flow in a constriction microchannel ChienHsuan Ko, Di Li, Amirreza Malekanfard, YaoNan Wang, LungMing Fu, Xiangchun Xuan Electroosmotic flow is the method of choice for transport fluids and samples (along with electrophoresis if charged) in micro and nanofluidic devices. However, the study of electroosmotic flow has to date been mainly focused on Newtonian fluids despite the fact that many of the chemical and biological fluids exhibit nonNewtonian characteristics. We present in this work a systematic experimental study of the fluid rheological effects on electroosmotic flow of viscoelastic solutions in a constriction microchannel. We find that the fluid elasticity effect does not change significantly the electroosmotic flow pattern while the fluid shearthinning effect may cause pairs of fluid circulations before to after the channel constriction. 

KP1.00129: Exsolving twophase pipeflow Victoria Pereira, Andrew Fowler Exsolving twophase flows occur in systems such as oil wells and volcanoes, where the exsolution of dissolved gas is due to depressurisation of the flow along the vertical conduit. We consider such a system with a liquid inflow containing a saturated concentration of dissolved gas at high pressures. Along the pipe, as the pressure decreases, dissolved gases exsolve and a twophase bubbly flow is initiated. We will present a twofluid model that explicitly accounts for the exsolution of the dissolved gas. Assuming thermodynamic equilibrium through Henry’s law for the dissolved gas concentration results in the unexpected prediction that a foam is rapidly formed. A possible reason for this is that nonequilibrium nucleation and bubble growth occur. We therefore generalise the twophase flow model to include nonequilibrium dynamics. A critical parameter controlling the rate at which exsolution occurs is found. We discuss solutions of the new model to illustrate the effect of this parameter on the flow. 

KP1.00130: Effect of nanoparticles on the spray characteristics of jet fuels at elevated ambient conditions Kumaran Kannaiyan, Reza Sadr Dispersion of high energetic metal nanoparticles in aviation fuels has gained interest in the recent years due to its potential for the enhancement of combustion characteristics. However, nanoparticle dispersion in liquid fuels can affect fuel atomization process, and in turn, the combustion and emission characteristics. Therefore, it is essential to have a thorough knowledge of the atomization characteristics of nanofuels (liquid fuels dispersed with nanoparticles) to better understand the latter processes. This work presents results of the macroscale atomization characteristics of nonreacting alternative, gastoliquid (GTL), jet fuel based nanofuels using a pressure swirl nozzle in an inert environment. The macroscopic spray characteristics such as spray cone angle, liquid sheet breakup, and liquid sheet velocity are determined by employing shadowgraph imaging technique. The effects of nanoparticles concentration and ambient pressures on the spray characteristics are discussed. The presented macroscopic spray results demonstrate that the nanoparticles dispersion at low concentrations affects the spray in the nearnozzle region. 

KP1.00131: Slip and NoSlip Flow in Micro and NanoPorous Media Md Minhajul Islam, D. Jed Harrison It is now more evident that the noslip boundary condition loses its accuracy in the case of micro or nanoscale fluid flows. We develop micro or nanoporous media having closepacked structures. A time of flight photobleaching velocity measurement technique is employed to determine the permeability and porosity of the media. Throughout the applied pressure range (1002000 psi), the Newtonian fluids irrespective of their wetting property exhibit very low Reynolds number (<0.003). This laminar flow pattern validates the applicability of Darcy’s law for our microporous system (106176 nm of hydraulic radius). Our results show that a linear relationship exists between permeability and porosity. The pressure driven flow experiment for noctane through silica porous bed confirms the existence of slip flow. The measured slip length values are 1220 times higher, compared to the theoretically predicted result from a molecular dynamics study. However, in presence of an aqueous film on the silica porous bed, the effective permeability for noctane is lower compared to the absolute permeability, even in its slip boundary condition. The measurement approach is a useful method to evaluate multiphase flow in nanoporous media. 

KP1.00132: Slipenhanced convective ion transport through ^{}sub1nm graphene oxide channels ChihChang Chang, DaoMing Chang, HungWei Chang Fast transport of water inside carbon nanotubes and graphenebased nanomaterials due to the surface slippage has been addressed in the past years. It is expected to enhance nanofluidic ion flow, such as electrical current and streaming current. In this work, ion transport in sub1nm nanochannels constructed by graphene oxide was investigated via electrical measurements. The experimental results showed that the electrical conductance at high salt concentration is significantly higher than the bulk conductance. According to the electrokinetic theory, the electrical conductance contributed from the slipenhanced electroosmosis (EO) has a scaling law of bσ^{2}, where b and σ are slip length and surface charge density, respectively. It implies that slipenhanced electrical conductance becomes considerable at the condition of high surface charge density, e.g. high pH value and salt concentration. As a result, we inferred that the convective ionic current is greatly enhanced by slip EO at high salt concentration. Based on the charge regulation model, the slip length of 10~20 nm was estimated, which is consistent with the value reported in the literature. 

KP1.00133: Understanding the dynamics of volumetric solar receivers Benjamin HerrmannPriesnitz, Williams R. CalderónMuñoz, José M. Cardemil, Rubén M. Fernández Volumetric solar receivers are known to exhibit choked flow regions and hotspots above a critical irradiance value, resulting in catastrophic failure. This phenomenon is commonly and incorrectly attributed to "flow instabilities". A dimensionless lumped model is formulated to investigate the coupled dynamics between the mass flux of fluid, the fluid temperature and the solid matrix temperature in the receiver. The choked flow solution is successfully identified as the upper branch of a cusp bifurcation, where the bifurcation parameter involves the ratio of irradiance to pressure drop through the absorber. The phase portrait of the system is depicted for different parameter values to provide physical intuition of the dynamics of the absorber for different operating conditions. The present analysis elucidates limitations and special considerations for volumetric solar receivers that are essential to advance the maturity of the technology. 

KP1.00134: Fractal Measures in Paper Marbling Michelle Wellman, Spencer A Smith Paper marbling is an old art form with major traditions in Europe, Turkey (Ebru), and Japan (Suminagashi). Creating marbled paper involves floating paints on the surface of a liquid bath, potentially using tools like combs or a stylus to stir the fluid, and transferring the resulting pattern to paper. There are a wealth of fluid dynamic concepts that marblers use to create specific effects, from modifying the Reynolds number to get a range of behaviors (Stokes to weakly turbulent) to varying the paint's surface tension to get Marangoni flows. Here we view the formation of patterns through the lens of nonlinear dynamics and, in particular, chaotic passive scalar advection. Classic work by Ott et al. showed that repeated application of a chaotic areapreserving map concentrates the gradient of the scalar on a set that is generically fractal and results in specific restrictions on the fractal dimension spectrum. Through a collaboration with professional marblers, we have numerically tested these ideas on highresolution scans of marbled paper created by the repeated action of a combing process. The beautiful patterns that emerge clearly show the fractal measures inherent in the art of paper marbling. 

KP1.00135: Refined Neutrosophic Trait Florentin Smarandache We measure a trait by computing the degree of <A> and the degree of <antiA>, so each human is on the spectrum between two opposites, and the human’s position on the spectrum is varying (is dynamic). There is no individual that entirely (100%) fits a trait; this may occur only in an idealistic way. Of course, the constants: antiThr, +Thr, and ε depend on each antiTrait/Trait pair, so they may be different from an antiTrait/Trait pair to another antiTrait/Trait pair. These constants are determined by psychological experts. If the degree of the Trait is greater than or equal to the Trait’s threshold (ThT), then the individual is characterized by this Trait. Similarly, if the degree of antiTrait is less than or equal to the antiTrait’s threshold (antiThr), then he/she is characterized by the antiTrait. In a neighborhood of the midpoint, [ε, ε], it is the most confused (indeterminate) degree (almost half antiTrait and half Trait) or antiTraitTrait blend. 

KP1.00136: Experiments of a sphere settling in simple shear flows of yield stress fluids Mohammadhossein Firouznia, Ramin Mehrani, Bloen Metzger, Guillaume Ovarlez, Sarah Hormozi We present our preliminary experimental results on the flow induced by a settling sphere in a yield stress fluid with and without a cross shear flow. We investigate creeping flows and we use particle image velocimetry and particle tracking velocimetry to analyze the flow and measure the settling velocity. We show a breaking of the foreaft symmetry in the direction of gravity and relate this to the rheological properties of the fluid. Also, we provide an estimation for the shearinduced sedimentation of an isolated sphere in a real yield stress fluid including elastic effects. 

KP1.00137: Numerical simulation of viscoplastic fluid flow between two parallel plates with triangular obstacles Nariman Ashrafi, Ali Sadeghi, Seyed mahmood Kia Obstruction of transfer lines in pipes and ducts or heat exchangers due to the sedimentation of solid particles or interference of outer objects can cause many problems and in severe cases total blockage of the transfer systems. In this research the flow of viscoplastic fluid is simulated between two flat plates with triangular obstacles numerically. Numerical findings suggest that with increasing the flow index, the intensity of vortices after obstacles diminishes in both cases of shear thinning and shear thickening states of the material. Furthermore, a method have been used to determine a constant viscosity of the fluid in each point and instance of the simulation and as the results the Reynolds numbers are obtained as a criteria of the flow instability. Basic numerical results are validated with empirical findings. 

KP1.00138: A mesoscopic thermodynamic approach for microstructures within the carbon fibers precursory mesophase pitch Caio César Ferreira Florindo, Adalberto Bono Maurizio Sacchi Bassi The present study employs a thermodynamic approach different from the conventional one to analyze, describe, and predict thermodynamic and mechanical properties of carbon fibers. On the mesoscopic space, new balance equations for the microdomains are deduced by considering their size and orientation as internal degrees of freedom. Evolution equations for the size and orientation of crystalline microdomains are also proposed. Compared to the usual continuum theory, additional fluxes into an orientation and direction space occur. These are constitutive functions, like internal energy, heat flux and stress tensor. By considering a modified form of the microdomain size evolution equation, it is possible to describe the low and intermediate shear rate regions. The overall evolution of the microdomain size, in both the shear inception and relaxation processes, is well described in agreement with phenomenological observations. Moreover, the calculations of steady shear flow properties such as viscosity, anisotropy, and primary normal stress difference, establish a new scheme for the mesophase pitch rheology in the low shear rate region. 

KP1.00139: Rheology and SelfRecovery of Ionomers Tanja Tomkovic, Julian Humpf, Savvas Hatzikiriakos Using a rotational rheometer equipped with a coneandplate partitioned geomtery, and an extensional fixture (SER), a rheological characterization of several commercial ionomers has been carried out including the determination of the linear viscoelastic moduli, the damping function and the tensile stress growth coefficient (extensional viscosity). A rheological method has been developed to assess the selfrecovery capabilities of ionomers using stress relaxation and recovery experiments. Moreover, peeling tests have been performed to quantify the selfhealing capabilities of these ionomers. Their behaviour has been compared with that of conventional polymers such as lowdensity polyethylene. 

KP1.00140: Functional Relationships between Scaling Groups and Oil Recovery in Miscible Displacements Ridha Gharbi The displacement of one fluid by another is the basis of many processes, such that in the remediation of contaminated aquifers and in Enhanced Oil Recovery (EOR) processes. These processes are modeled first in the laboratory before they are tried in the field. When the laboratory results are presented in scaled format, it is then possible to use the results of this system (lab scale) to predict the behavior of another similar system, the one of actual interest, the prototype. In this study, a rigorous procedure of inspectional analysis was used to determine the independent dimensionless scaling groups that describe miscible displacements of oil by a solvent. A twodimensional, heterogeneous, anisotropic vertical cross section with constant porosity and dip angle was assumed. Results show that scaling miscible displacements requires the matching of thirteen dimensionless scaling groups. Finemesh numerical simulation was then performed to develop the functional relationships between these scaling groups and the fractional oil recovery obtained from such displacement. This relationship can be used as a quick prediction tool for the fractional oil recovery for any combinations of the scaling groups, thus eliminating the need for the expensive simulations. 

KP1.00141: A simple analytical model for estimating the dissolutiondriven instability in a fluid saturated porous medium Layachi Hadji 

KP1.00142: Abstract Withdrawn We present results from largeeddy simulations (LES) of turbulent channel flow at high Reynolds number of order O(10^{9}) with suspended charged particles. The overarching goal of this work is to develop an LES framework for the simulations of sandstorms as charged particleladen flow. The present investigation relies on simulating multiphysical twophase (fluid and charged particles) turbulent flows in which the fluid flow is governed by the NavierStokes equations in a LES setting employing the stretched spiral vortex subgridscale model and a virtual wall model, while sand particles are modeled using an Eulerian approach via a simplified version of the Direct Quadrature Method of Moments. The electrostatic approximation is used to model the interaction of charged solid particles. Preliminary results show fluctuations of the electrical field in the flow in reasonable agreement with some field observations in sandstorms. The effects of different sand particle distributions, and turbulent intensities on the rootmeansquare of the generated electric fields will be examined. 

KP1.00143: Design and analysis of a detonationdriven mechanism for needlefree liquid jet injection Rocco Portaro, Han Xu, Yanting Li, Jad Sadek, Hoi Dick Ng Needlefree liquid jet injection for drug delivery is a biomedical concept aimed to reduce many drawbacks associated with the use of hypodermic needles such as biohazard waste, cross contamination and needle phobia. One of the key elements which limits the current technologies is the ability to provide sufficient power to generate a highspeed liquid jet with a velocity on the order of 100 to 200 m/s, created by using a piston to compress a column of fluid through a microorifice. This jet pierces the skin and effectively delivers larger quantities of highly viscous medication to a target area at different skin layers. This study experimentally explores the idea of harnessing the energy release from a gaseous detonation for the high power requirement necessary to drive the injection piston and pressurize the medication. The feasibility and performance of the detonationdriven mechanism are assessed against available technologies such as airpowered and servocontrolled, high precision injection systems. The comparison aims to illustrate basic relationships between different injection characteristics and detonation parameters used in this proposed controlled release process. 

KP1.00144: LES/FDF studies of probability distribution of mixture fraction in inhomogeneous inlet turbulent jet flames Haifeng Wang, Pei Zhang, Robert S. Barlow, Assaad R. Masri Mixture fraction is a key parameter that can be used for quantifying and modeling mixing in turbulent nonpremixed, partially premixed, and stratified flames. It is a central quantity in many existing combustion models such as the flamelet models and the conditional moment closure. Developing capabilities to accurately predict mixture fraction is thus crucial for turbulent combustion modeling. Focus in the past has mainly been put on the prediction of the loworder moments such as the mean and variance of mixture fraction. The prediction of the full statistical information of mixture fraction has not been thoroughly studied. In this work, we examine the predictive capability of largeeddy simulation (LES)/filtered density function (FDF) for the probabilistic distribution of the mixture fraction. A series of piloted methane jet flames with inhomogeneous inlet flows is chosen as the test case which has detailed measurement data for the distribution of the mixture fraction. Different statistical distributions are examined such as the singlepoint PDF and the FDF. The capability of capturing these distributions by using LES/FDF is examined thoroughly. 

KP1.00145: An experimental study on fracturing flows of Newtonian fluids Ahmadreza Rashedi, Mohammad Sarabian, Mohammadhossein Firouznia, Guillaume Ovarlez, Sarah Hormozi We show our preliminary experimental results on the dispersion of solid in fracturing flows of Newtonian fluids. We have designed and built a unique experimental setup that resembles a fracture configuration. A mixed particle image and tracking velocimetry technique is used to visualize the flow. Our aim is to provide well resolved experimental results to investigate the physical mechanisms responsible for dispersion of solid in fracturing flows in various regimes and to refine the available model frameworks. 

KP1.00146: Normal Stresses of sheared Suspensions in crystalline States Behrouz Abedian, Behrouz Abedian This presentation extends a geometric analysis on viscosity of solutions in crystalline states to their respective 2^{nd} normal stress . This extension establishes a key relationship between the structuredsuspension viscosity and its normal stress components . For a noncolloidal mixture, it is shown that the 2^{nd} normal stress equals the averageshear stress on the solid particles plus a constant dependent on the solutions’ crystalline state. The analysis deduces that the second normal stress is negative always when the system possesses ordered states. Experimental and numerical data on for noncolloidal equalsize spherical suspensions reveal three distinct particle concentration spectra each characterized by the effective crystalline state of the particles in the mixture. A comparison of this analysis and experimental data on suggests a crystalline transition from simple cubic to facecentered cubic states when the particle volume fraction exceeds 45%, in agreement with light scattering observations and viscosity data. 

KP1.00147: Errors in Energy Landscapes Measured with Particle Tracking Michal Jozef Bogdan, Thierry Savin Tracking Brownian particles is often employed to map the energy landscape they explore. Such measurements have been exploited to study many biological processes and interactions in soft materials. Yet video tracking is irremediably contaminated by localization errors originating from two imaging artifacts: signal noise (or "static" errors) and motion blur ("dynamic" errors). We derive an equation for the measured energy landscape contaminated by these errors, which notably elucidates the presence of false doublewell minima in the apparent potentials reported in recent studies. Our formula also allows for the development of postmeasurement corrections schemes for reconstructing true potentials from the measured ones. 

KP1.00148: Rheology of a soft jammed interfacial solid Dani Medina, Benjamin Kauffman, Brian Kroger, Juan A. Ortiz Salazar, Chen Fan, Xiang Cheng, Nathan C. Keim Particles adsorbed at an oilwater interface form a soft jammed solid, due to their longrange electrostatic repulsion. We measure the rheology of this material with a sensitive custombuilt interfacial shear rheometer. The device uses permanent magnets to trap and control a needle that is adsorbed at the interface [Tajuelo et al., J. Rheol. 2016], with simultaneous microscopy that tracks the motions of individual particles in the material. We describe the instrument and present preliminary results on the evolution of the system's rheological properties as we "train" a memory in the system through oscillatory shear. 

KP1.00149: Quantitative Modeling of Growth of Colloid Nuclei Lou Kondic, Michael A Lam, Boris Khusid, William Meyer We have formulated a model that allows for obtaining quantitative results describing growth of colloid nuclei. The model includes the information regarding the equation of state resulting from molecular dynamics (MD) simulations, and provides the route for extraction of the kinetic prefactor that is challenging to obtain via experiments or MD simulations. Our elaborate model combined with extensive and accurate simulations allows one to compare the findings to both microg experiments carried out on ISS, and Earth based ones. As an outcome, we conclude that particle scale properties are not responsible for the observed differences between the experiments carried out under different gravitational field strengths, but instead that collective effects may be relevant. Therefore, our results suggest directions for future research, in particular those regarding formulation of even more complete models describing growth of colloid nuclei. 

KP1.00150: Adsorption of graphene oxide at the oilwater interface: effects of concentration and temperature Boyao Wen, Bofeng Bai As a twodimensional material, graphene oxides (GOs) have attracted much attention due to their interfacial activity, easy functionalization, simple preparation, among others. Recently, some work demonstrated the amphiphilicity of GOs at the oilwater interface. Considering that an analysis of the adsorption behaviors of GOs at the interface is crucial to understand the amphiphilicity of GOs, we employ molecular dynamic method to explore the effect of concentration and temperature on the adsorption of GOs at the decanewater interface. The results show that the GOs adsorb at the interface with their surface parallel to the interface. With concentration increasing, the configuration of GOs changes from tiled form to stacks. At higher concentration, the GOs even are perpendicular to the interface. The transition of configuration of GOs at the interface induces a nonlinear variation of interface tension, which we think is dominated by the hydrogen bonding at the GOs. In addition, with temperature rising, the interfacial tension decreases obviously because the arrangement and assembly of GOs at the interface is accelerated. 

KP1.00151: Experimental observation of drift wave turbulence in an inhomogeneous Multipole cusp magnetic field of MPD A. D. Patel, M. Sharma, N. Ramasubramanian, P. K. Chattopahyay This paper presents a detailed study on the controlled experimental observation of drift wave instabilities in an inhomogeneous Six pole cusp magnetic field generated by an inhouse developed Multipole line cusp magnetic field device (MPD) [A. D. Patel et al., Rev. Sci. Instrum. 44, 726 (2018)]. The device is composed of six axially symmetric cusps and noncusp (in between two consecutive magnets) regions. The observed instability has been investigated in one of these noncusp regions by controlling the radial plasma density gradient with changing pole magnetic field which is a unique feature of this device. It has been observed that the frequency of the instability changes explicitly with the density gradient. Moreover the scale length of plasma parameters, frequency spectrum, crosscorrelation function, and fluctuation level of plasma densities has been measured in order to identify the instability. The cross field drift velocity due to fluctuation in plasma parameters have been measured from the wave number frequency S (k_{z}, ω) spectrum and verified with the theoretical values obtained from density scale length formula. Further from the S (k_{z}, ω) spectrum it has been found that the drift velocity alternates the sign in the consecutive noncusp regions. 

KP1.00152: The Reynoldsaveraged Bernoulli equation and its application to internal flows Ben Trettel The Reynoldsaveraged form of the Bernoulli equation is derived and applied to internal flows. Previous researchers have attempted with limited success to relate the turbulent kinetic energy in screens and nozzles to internal flow loss coefficients. The turbulent Bernoulli equation confirms that turbulent kinetic energy and dissipation in internal flows are related to the loss coefficient. The loss coefficient can be viewed as a simple empirical turbulence model. Further, the turbulent Bernoulli equation confirms the hypothesis of several researchers that the failure of previous screen turbulence theories is partly due to the neglect of dissipation. However, including both dissipation and turbulent kinetic energy may not be sufficient, as there are many other turbulent terms which require accounting as well. As an example of the practical application of the turbulent Bernoulli equation, the turbulent kinetic energy at the outlet of a nozzle, e.g., for an atomizer, is estimating by modeling the unclosed terms. 

KP1.00153: TimeSeries Analysis of Intermittent Velocity Fluctuations in Turbulent Boundary Layers Mohsen Zayernouri, Mehdi Samiee, Mark M. Meerschaert, Joseph Klewicki Classical turbulence theory is modified under the inhomogeneities produced by the presence of a wall. In this regard, we propose a new time series model for the streamwise velocity fluctuations in the inertial sublayer of turbulent boundary layers. The new model employs tempered fractional calculus and seamlessly extends the classical 5/3 spectral model of Kolmogorov in the inertial subrange to the whole spectrum from large to small scales. Moreover, the proposed timeseries model allows the quantification of data uncertainties in the underlying stochastic cascade of turbulent kinetic energy. The model is tested using wellresolved streamwise velocity measurements up to friction Reynolds numbers of about 20,000. The physics of the energy cascade are briefly described within the context of the determined model parameters. 

KP1.00154: Turbulence Enrichment using Generative Adversarial Networks Sravya Nimmagadda, Akshay Subramaniam, Man Long Wong, Raunak Borker, Sanjiva K Lele Generative Adversarial Networks (GANs) have been widely used for generating photorealistic images. A variant of GANs called SRGAN has also been used successfully for image superresolution. However, when such generative models are used for physical data, the governing equations may not be obeyed by the generated data. In this work, we develop a method for generative modeling of turbulence. We incorporate a physics informed learning methodology by a modification to the loss function that tries to minimize the residuals of the governing equations for the generated data. The proposed method is demonstrated on isotropic turbulence data at Taylor Re ~ 17 obtained using a pseudospectral method on a 64^3 grid. 1260 statistically decorrelated snapshots are collected of which 920 are used to train two models: a supervised residual network and a GAN, both of which are then shown to outperform bicubic interpolation. Using the physics informed learning is also shown to significantly improve the model’s ability to respect the physical governing equations. The results of the GAN enrichment are compared to ground truth data through pointwise errors as well as statistical quantities like 3D energy spectra, longitudinal and lateral correlation functions and third order structure functions. 

KP1.00155: Exact thirdorder structure functions for twodimensional rotating stratified turbulence JinHan Xie, Oliver Buhler We apply Kolmogorov's isotropic turbulence theory to the twodimensional isotropic rotating stratified turbulence in a vertical plane with equal Coriolis and buoyancy frequencies. Contrary to the twodimensional turbulence, a downscale total energy flux is discovered, explained and justified by numerical simulations in different parameter regimes depending on the relative sizes of Ozmidov (Zeman) and forcing scales. Based on the KarmanHowarthMonin equation, exact expressions for the thirdorder structure functions, which are uniformly valid across the entire nondissipative range including the forcing scales, are derived by assuming a statistical balance between external random forcing and smallscale dissipation, and they show good agreements with numerical results. In addition, potential applications to interpreting measured geophysical fluid data are discussed. 

KP1.00156: Application of Frequency Dependent Proper Orthogonal Decomposition to TimeResolved Schlieren Data Extracted From a Supersonic MultiStream Rectangular Jet Ryan Masetta, Andrew S Tenney, Zachary P Berger, Mark N Glauser Frequency dependent proper orthogonal decomposition has been used in recent work to examine the structure of turbulence in various flow regimes and involves decomposing the flow into energyranked coherent structures along with extracting energy spectra. The resulting modes were used to investigate wavepackets of the KelvinHelmholtz type and the Orr type mechanism, which are differentiated by their modal and nonmodal behaviors respectively. In a similar manner, this technique of low dimensional modeling is applied to timeresolved schlieren data extracted from an experiment revolving around the investigation of a multistream rectangular nozzle flow. An instability arising from the merging of the core stream and additional bypass stream (third stream) inside the nozzle has been proposed as the physical mechanism driving a high frequency 34 kHz signal seen throughout the entire flowfield including the far field acoustics. Modal and spectral analysis through application of this technique to the schlieren data set can reveal information regarding the behavior of this instability, how it is propagated further downstream, and the propagation of information from other flow structures in the region of the nozzle exit. 

KP1.00157: Wave/PotentialVortex Dynamics within Stratified Shear Layer Turbulence Aaron Wienkers, Aditya Ghate, Sanjiva K Lele We explore the interaction between trapped internal gravity waves on the stratified shear layer dynamics and turbulence following breakdown of KelvinHelmholtz billows using threedimensional direct numerical simulations. A weakly inhomogeneous normalmode decomposition of the fields is proposed, and upon classification of the character of each mode from the meanflow linear stability analysis, is compared with that of the classic weaklynonlinear Wave/PotentialVortex decomposition. This diagnostic tool is finally employed to study the energy transfer among modes and between the propagating wave and turbulent vortex parts, shedding more light on the kinetic and available potential energy evolution. 

KP1.00158: Experimental measurement of the wake of a oscillating fish body model Sareta Gladson, Seth Brooks, Melissa Green Over eons of evolution, fish have evolved the innate ability to manipulate the fluid in their wake to facilitate their locomotion. The organization of the fluid in the wake consists of chains of vortex rings produced by a single flapping fin, which has previously been described using particle imaging velocimetry (PIV) water tunnel experiments. The goal of this study is to create a passively flexible fish model with nineteen rigid rib components that can pivot relative to each other. Using 20 3D printed body sections, brass pins, a laser cut caudal fin, a modified camshaft, and monofilament, the model is able to execute a simple traveling wave motion. In future versions of this model, the fish will be able to execute prescribed realistic movement as actuation will be based on the angle of turn and radii of the camshaft. This design allows for the wakes across a range of Strouhal numbers and caudal fin models to be visualized through PIV. The model approximates the natural movement of a fish without compromising the ability to collect consistent and reliable data. 

KP1.00159: Thrust analysis of a heaving flexible plate by force element theory ChinChou Chu, YungSheng Lin, Chien C Chang, JenJen Lin In this study, we have conducted a numerical study of a uniform flow over a flexible plate in heaving motion. The flow is assumed to be laminar with the Reynolds numbers fixed at Re=500, and the Strouhal number St ranging from 0.1 to 0.6. The flow is complicated with threedimensional vortices generated all around the finite body, in addition to the unsteady motion of the plate. In particular, we performed the force element analysis to examine the detailed force mechanisms of how individual flow components contribute to the thrust on the heaving plate. It is often considered in the literature that the flapping tail has thrust mainly produced by the wake behind the body (such as the theory of reverse Kármán vortex). However, the present analysis shows that the vorticity in the wake comprises around 30% of the total vorticity thrust, which in turn comprising about 22% of the total thrust. Comparable contributions come also from the regions direct above and below the heaving plate (mainly including the attached vortices) as well as from the two side regions (mainly including the tip vortices) next to the flexible plate. 

KP1.00160: Modeling Filtering Process Using Stochastic Simulations of MonteCarlo Type Catherine Sousa, Lou Kondic, Linda J. Cummings Filtration media have improved over the years to address a multitude of problems but continue to lose efficiency over a period of time due to membrane fouling which occurs even when the pores are much larger than the suspended particles via particle deposition on the pore interior walls. The focus of this research is to develop specifications for the optimal pore shape in the membrane media that maximize the filter lifetime, or the time at which pores of the membrane close fully, while ensuring adequate removal of impurities. For this purpose, we have developed stochastic simulations of MonteCarlo type to simulate fouling and to study the effect of various parameters on the performance of the pore. We focus particularly on the probabilities of particles sticking to each other and to the pore walls, as well as on the influence of a crossflow. Our model is used to investigate the performance of a membrane given multiple pores positioned next to each other. In this model, the parameters studied included the strength of the crossflow along with the pore size variation, both in the depth of the membrane and in the direction of the crossflow. We use our results to draw conclusions about optimal filtration scenarios. 

KP1.00161: GPGPU Accelerated MACSOLA Immersed Boundary Method Somnath Roy, Apurva Raj, Anomitro Datta A GPU accelerated discrete finite difference based efficient IBM is validated by studying the motion of passive flexible flaps in a two dimensional flow field. A FEM based beam model is used for the deforming flaps and the partitioned coupling method is used to study the FSI. Solution Algorithm (SOLA) and Marker and Cell (MAC) method are coupled to satisfy the mass conservation equations. This coupling avoids the cell regeneration and/or reconstruction algorithms in the moving boundary problems. The coupling algorithm improves the granularity in the estimation of pressure correction near the immersed boundary. The coupled pressure correction solver is accelerated on a NVIDIA P100 GPGPU using OpenACC. The performance of accelerating the pressure correction solver on the GPU and through multicore CPUs is also discussed. 

KP1.00162: Lowcost, transparent, handson fluid mechanics and heattransfer experiments for the classroom Aminul Islam Khan, Negar Beheshti Pour, Fanhe Meng, David B Thiessen, Prashanta Dutta, Robert F Richards, Paul Golter, Bernard Van Wie Small scale desktop module can eliminate many common misconceptions in fluid mechanics and other related areas. Modules have been implemented in standard classrooms in undergraduate mechanical and chemical engineering courses to teach the energy concepts behind flow through a venturi, flow in a pipe, and heat transfer between hot and cold streams in a heat exchanger. A common student misconception related to the venturi is that the pressure should go up as the liquid flows through the throat because it is being “squeezed.” Manometer tubes molded into the handson venturi module clearly demonstrate that the pressure is much lower in the throat than it is upstream or downstream of the throat. A misconception related to continuity of flow in a pipe is that the velocity should decrease with distance because of friction. This is countered using a plastic ball entrained in the flow to show that it does not slow down. Several modules that mimic industrial heat exchangers allow students to measure heat duty and see its dependence on flow rate and temperature driving force. A module that allows students to see evidence for the thermal boundary layer on a heated cylinder in water can supplement active learning. 

KP1.00163: Flow instabilities in volatile sessile droplets under evaporation in weightlessness Sanjeev Kumar, Shaokang Cui, Zhiliang Li, Dongsheng Wen, Marc Medale, David Brutin The flow pattern and instabilities occurring during evaporation are still under investigations and their origin is still debated. We are comparing an ethanol drop evaporating onto a heated substrate under weightlessness conditions and with pinned contact line with a 3D unsteady computation of thermoconvective instabilities to determine with accuracy the type of instabilities. Our onesided model, devoid of fitting parameters, demonstrates quantitative agreement with experimental data and confirms that experimentally observed instabilities are driven by thermocapillary stress, and not by the gas convection. By creating creating a numerical infrared image, we can conclude with certitude that the experimentally observed thermoconvective instabilities in evaporating sessile drops of volatile liquids, which in infrared spectrum look similar to hydrothermal waves, are actually nothing else than unsteady BénardMarangoni instability. 

KP1.00164: A spacetime integral minimisation method for the reconstruction of velocity fields from measured scalar fields. Jurriaan Gillissen, Alexandre Vilquin, Hamid Kellay, Roland Bouffanais, Dick Yue Scalar image velocimetry (SIV) reconstructs velocity vectors from scalar field measurements. The usual technique involves minimising a cost functional, that penalises the deviation from the scalar conservation equation. This approach requires the scalar measurements to be sufficiently resolved and relatively noise free, such that space and time derivatives can be accurately evaluated. To alleviate these requirements, we propose an improved SIV scheme, which does not require evaluating the space and time derivatives of the measured scalar field. Improved velocity reconstruction is demonstrated for a two dimensional, synthetic field. We furthermore apply the scheme to interferograms of the thickness field of a turbulent soap film. The reconstructed velocity fluctuations are within 10 % of laser Doppler velocimetry measurements. 

KP1.00165: Torsional flow of a viscoelastic fluid over soft surfaces Bidhan Chandra Experiments are performed to show that the suppression of purely elastic instability for the torsional flow of a polymeric solution over soft solids is dependent on the shear modulus of the soft surface. The shear rate at which viscosity shows an increase is the critical shear rate for the onset of purely elastic instability. It was shown that in presence of a soft surface in between the top moving plate and the bottom plate there is a suppression of purely elastic instability . However those experiments were done only for a particular shear modulus of the soft surface. In the present work we perform the flow experiments by keeping soft surfaces of varying shear modulus. We explore the role of varying shear modulus on the onset of the purely elastic instability. hence we conclude that the suppression of purely elastic instability is dependent on the shear modulus of the soft surface prepared. 

KP1.00166: Large ellipsoids rising in quiescent fluids and turbulent flows Jelle Will, Varghese Mathai, Dominik Krug, Sander Huisman, Detlef Lohse, Chao Sun Solid particles in nature or industrial applications are almost never perfectly spherical; there is always some measure of anisotropy in their topology. Understanding the effect of geometry on the rise trajectory and dynamics of such particles is therefore highly relevant, as is their interaction with freestream turbulence. Many particles are well described by assuming them to be ellipsoidal with aspect ratio χ = h/d. We experimentally investigate light (buoyant) particles of density ratio Γ = 0.52, all with a volume equivalent spherediameter of d = 0.02m and a Galileo number of 6300. The aspect ratio is varied from χ = 0.25, oblate, to χ = 4 prolate. Using translational and rotational particle tracking, we investigate the particle behaviour when rising through a quiescent fluid and a turbulent flow of Re_{λ} ≈ 300. A strong dependence of drag coefficient on aspect ratio is found. Generally the value of C_{d} is reduced for turbulent flow compared to a quiescent liquid. Further, we characterise the particle kinematics and dynamics in terms of a Strouhal number and orientation and acceleration statistics. 

KP1.00167: Water droplet impact behaviour on cold hydrophobic surface Changseok Park, HeeChang LIM Experimental study of a droplet impingement on a hydrophobic surface has been performed by visualizing the temporal variation. The NaCl solution was mainly used and, droplets were formed at a tip of flat needle by using electrostatic potential. The free falling droplet impacted on a cold hydrophobic metal surface, which was visualized by using a highspeed camera and LED light. After having impingement on the surface, the droplet has a process of rebound, recoil and splash. Depending on the size of the droplet, we observed that after a collision, the dynamic behaviour of the droplet, the size of the droplet spreading and splashing, which depends on the size of the volume. 

KP1.00168: Fabrication of Spherical Capshaped Polystyrene Microlenses via Transient Ouzo Effect Yuliang Wang, Binglin Zeng, Xuehua Zhang, Detlef Lohse Micro/Nano lensshaped objects fabricated on solid surfaces have extensive applications. It is of significance and challenging to achieve controlled formation of those microlenses. In this report, we presented a new approach to fabricate polystyrene (PS) microlenses on glass substrates using transient toluene droplets. We find that the addition of water droplets into a wellmixed toluene/ethanol binary solution will cause local and temporary oversaturation of toluene in the formed toluene/ethanol/water ternary solutions. This is referred to as “transient Ouzo effect”. The “transient Ouzo effect” results in the nucleation of toluene droplets on spin coated PS films on glass substrates. The PS films were then dissolved by the nucleated toluene droplets and formed toluene/PS mixture droplets. After the toluene was dissolved back into the ternary solutions, the PS microlenses were obtained on the glass surfaces. The influence of PS film thickness and toluene concentration in the toluene/ethanol binary solutions on the fabricated PS lenses was investigated, followed by the tuning of microlens contact angle through a thermal reshaping method. Moreover, experiments were conducted to verify that the fabricated lenses can achieve enhanced optical imaging with an improved resolution. 

KP1.00169: Cavity Measurement Inside Water Droplet on Superhydrophobic Surface Mohammad Alhazmi In this study, we show the dynamic of water droplets on the Superhydrophobic surface at low impact velocity. when the drop hits the surface, oscillation starts and the capillary waves formed a cylindrical cavity inside the drop and the cavity starts closing in a selfsimilar way until collapsing. We show that during receding the cavity collapses in different scenarios based on the impact velocity and the surface wettability. More importantly, observing for the first time highspeed (up to 5 million fps) visual records and considering optical distortion correction of the collapsing cavity. The experiment results of the cavity radius are compared with the modified RayleighPlesset equation for free cylindrical flow and good agreement is shown. 

KP1.00170: Experimental and Numerical Investigation of River Hydrokinetic Turbines for Water Pumping Applications Mohammad Fozan Ur Rab, Wajiha Rehman, Muzammil Ejaz, Fahad Ullah Qureshi, Muhammad Hassan This study is carried out to design a low head turbine which will utilize the kinetic energy of the flowing river stream to drive a water pump. When the turbine rotates, the coupled pump will pump the water to the specified location. Two to three such types of turbines will be installed in the river to fulfill the water requirement of the small town. Axial flow Hydrokinetic turbine design is chosen because it has high efficiency and fabrication ease. Initially, a scaled model of fullscale turbine and diffuser is fabricated and tested in a closedcircuit water tunnel. The same scaled model is also analyzed by using Computational Fluid Dynamics (CFD) and the numerical results are validated. The computational grid for numerical analysis contains approximately 5.5 million cells with average y+ value less than five and the komega SST turbulence model is utilized to close the system of Reynolds Average NavierStokes Equations. In future, a validated CFD model will be used to simulate the fullscale turbine prototype in actual river conditions and will be helpful in optimizing the design. 

KP1.00171: Experimental study of droplet formation of dense suspensions Gustaf Martensson, Fabian Carson As with the jet printing of dyes and other lowviscosity fluids, the jetting of dense fluid suspensions is dependent on the repeatable breakoff of the fluid filament into wellformed droplets. It is well known that the breakoff of dense suspensions is dependent on the volume fraction of the solid phase, particle size and morphology, fluid phase viscosity et cetera, see for example van Deen et al. (2013). The purpose of this study is to establish a deeper understanding of the formation process of droplets of dense suspensions. Previous experiments have utilised a filament breakoff device (FilBO) developed inhouse. These experiments utilise an ejection device based on rapid volumetric displacement of the fluid through a conical nozzle. The suspension samples consist of a resinbased flux and spherical particles with diameters of \(d_p = 525 \mu \)m with varying size distributions. A droplet of of the suspension with a volume of \(V_{\mathrm{drop}} = 250 \) nl is ejected from the nozzle. Correlations between droplet speed and the temporal development of the volumetric displacement will be presented. Further results relating breakoff length and rate versus particle diameter, volume fraction and probe speed will be presented. 

KP1.00172: Effect of rough surface on flow characteristics of turbulent boundary layer KwonHo Park, HeeChang LIM In this study, the characteristics of turbulent boundary layer in flow field on the rough surface were examined in boundary layer wind tunnel. The cube arrays patch has a pattern of staggered and aligned towards the windward direction. The boundary layer characteristics such as mean velocity, turbulent quantities were measured using thermal anemometry. Results show that turbulent boundary layer have been generated successfully on the roughness surface, and the boundary layer characteristics vary depending on the pattern of surface roughness. In order to validate the measurement data in wind tunnel, the turbulent boundary layer was also simulated using the numerical simulation. 

KP1.00173: Data Analytics on the Phase Behavior of Oil/Water/Surfactant Systems Shiyan Wang, Nathan Schultheiss, Sangtae Kim According to BP Statistical Review of World Energy in 2018, the total oil production in US in 2017 is about 13 million barrels per day (MBPD), which is even greater than that of Saudi Arabia (less than 12 MBPD). Thanks to the booming shale oil production, United States have become the world’s top oil exporter. In fact, two third of conventional crude oil in US Field is remained unproduced due to the physics of fluid flow. The techniques of chemical enhanced oil recovery could overcome the physical force holding hydrocarbons, and turn these accumulations into oil reserve. To enhance the oil recovery in the reservoir, many efforts have been made to apply surfactants into the injected water. For the oil/water/surfactant system, the goal is to form the phase ‘microemulsion’ to achieve the lowest interfacial tension. Therefore, it is critically important to achieve a great mixing phase behavior for the oil/water/surfactant system. In collaboration with the Pioneer Oil Company, our current effort is to better optimize the selection of surfactants, and the constituents of the surfactant blend, which turns to be a high dimensional problem. In addition to the conventional analysis, we employ the machine learning techniques to solve the system as a multinomial classification problem. 

KP1.00174: Investigation of membrane dehumidification by pervaporation Jungchul Kim, Dong Ho Kim, Young Kim, Keon Hu Lee, Seok Ho Yoon Controlling humidity is essential for a comfortable life and various technologies have developed for the dehumidification devices. Among the systems, we introduce a novel system including a vacuum pump and a membrane (fabricated by Prof. Seo, Young Soo, Sejong Univ.) that separates a feed chamber and a permeate chamber, connected with the vacuum pump. Both sides of the membrane are faced with the humid part (feed chamber) and the dry part (permeate chamber) at the same time, driving the water vapor, which is referred to as pervaporation. We measure the outlet humidity and the water vapor transport rate, the mass of vapor permeated through the membrane, under the various experimental conditions of different feed flow rates and feed chamber heights. As the flow rate increases, the outlet humidity is decreased, whereas the water vapor transport rate is increased. However, they are independent of the height in our experiment range. Combining mass transport theory and the volume conservation, we have established theories of the outlet humidity and the water vapor transport rate. The experimental data points are entirely consistent with our theory curves. Comparing the experimental results and the theories, we also have derived the membrane coefficient. 

KP1.00175: Direct Numerical Simulations and Characterizations of Multiphase Flows with Complex Topology Changes in a Turbulent Channel Jiacai Lu, Gretar Tryggvason The interface between different phases in multiphase flows often undergoes repeated topology changes due to the breakup and coalescence of fluid masses. With the increase of the volume fraction of one phase, the flow structures change from dispersed bubbles/drops to more complex irregular shapes, and the fluids are often highly interconnected. We place bubbles in a threedimensional turbulent channel flow, with the average void fraction varies from 5% to 25%, and use a front tracking/finite volume numerical method for direct numerical simulations of the flows till they reach statistically steady states. The evolutions of various integral quantities, such as the average flow rate, wallshear, and interface area are monitored and compared for these different cases. The structures of the flows, at statistically steady state, are characterized and quantified with the distributions of some statistical descriptors, such as bubble size, interfacial area density, interface shape distribution and interface normal distribution. 3D twopoint correlation functions and primary component analysis (PCA) are also employed for the quantification and reducedorder representation of the structures. 

KP1.00176: Analyzing airingress currents in Gascooled nuclear reactors using Kramers Moyal expansion Daniel Gould, Abhinav Gairola, Hitesh Bindra During a loss of coolant accident in High Temperature Gascooled Nuclear Reactors, a break in the coolant system will allow air ingress into the high temperature reactor and can negatively impact the core thermal behavior. Airingress rates are supposed to be influenced by molecular diffusion during initial stages and global natural convection at later stages where reactor cavity air is circulated through the core due to temperature differential. But the transition times predicted by the diffusion theory are much larger than experimental results at high temperature, thus role of convection currents even before the transition stage is suspected. Velocity timeseries data from hot wire anemometer located at the opening is analyzed to quantify the role of convection vs diffusion modes. It was evident with the pdfs of velocity data that kurtosis increases with increase in temperature. Kramers Moyal analysis was performed to disentangle the drift and diffusion coefficients of the velocity time series measured in a test section designed to mimic the loss of coolant accident in an HTGR. Relative values of these coefficients together with the probability density functions of the velocity fluctuations were compared at different temperatures. 
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