Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session Q11: Experimental Techniques: Quantitative Flow Visualization II |
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Chair: Joe Katz, Johns Hopkins University Room: 3B |
Tuesday, November 26, 2019 7:45AM - 7:58AM |
Q11.00001: Novel Particle Shadow Tracking Velocimetry Technique Carlos Echeverria, David Porta, Catalina Stern, Enrique Guzman We present a novel, non-invasive particle tracking velocimetry technique, called Particle Shadow Tracking Velocimetry (PSTV), which is based on the shadows cast by the process particles conveyed within a gaseous phase. Ad hoc digital filters were designed and implemented, in order to detect these solid particles with a high degree of precision. To this end, the methodology relied on the measurement of an Ultra Depth of Field (UDOF) distance required for the correct determination of the detection volume. The PSTV technique produced accurate velocity field values when tested with a validation experiment. We show that the determination of the volume of study is crucial for the correct measurement of the velocity field. To do so, we studied a biphasic solid-gas flow in the compressible regime; the solid phase consisted of a polydisperse granular material with an average size of 0.3mm. [Preview Abstract] |
Tuesday, November 26, 2019 7:58AM - 8:11AM |
Q11.00002: Experimental investigation of the clustering of particles in non-Newtonian liquids in stirred vessels Giovanni Meridiano, Wehliye Hashi Wehliye, Luca Mazzei, Panagiota Angeli The blending of solid particles with liquids is a crucial step in many manufacturing processes; it is regularly encountered in industrial sectors like healthcare, pharmaceuticals and food processing. Stirred tanks are commonly used in industry to process solid -- liquid mixtures principally because of their flexibility, relative construction simplicity and availability. Recent studies have proposed stirred tanks as a tool to achieve the separation of the solids suspended in Newtonian liquids (Wu \textit{et al.} 2015). In this study, the investigation of the clustering of particles in non-Newtonian liquids in stirred vessels is presented. A viscoelastic liquid was chosen that had matching refractive index with the suspended particles and a novel combination of \textit{PLIF} and \textit{PIV/PTV} techniques was used to measure the velocity fields of the particles and of the fluid simultaneously as well as the evolution of the concentration of the particles in the tank. It was found that the particles accumulated in the cores of the vortices. In addition, the accumulation speed was found to be dependent on the viscoelastic properties of the fluid and on the diameter of the solid particles [Preview Abstract] |
Tuesday, November 26, 2019 8:11AM - 8:24AM |
Q11.00003: Development of a velocity and concentration measurement method for $CO_2$ dissolution in brine within a Hele-Shaw cell Mengye Zhao, Kenneth Kiger, Ankur Kislaya, Jerry Westerweel We perform quantitative velocity and concentration measurement within a Hele-Shaw cell Rayleigh-Benard convection as CO$_2$ dissolves into brine. The velocity is measured using PIV under large depth-of-field and gap-wise Poiseuille flow conditions, making reliable quantitative velocity measurement difficult due to the large velocity gradient across the gap. Previously, particle sorting has been purposed and validated as a means to resolve this problem. The method flushes particles along the cell until all have migrated to their gap-wise equilibrium plane, thus providing an unambiguous velocity magnitude. However, in order to accomplish the sorting, a large portion of the test cell will not be usable for measurement. We purpose a new method to overcome this limitation. We first conduct PIV without sorting particles to obtain only the velocity direction. This provides the value of the in-plane velocity ratio ($u$/$v$) at every $x,y$ coordinate pair. We then obtain the CO$_2$ concentration map using fluorescent emission of a Ph sensitive dye. Having mapped the concertation, we combine the $u/v$ information and solve the CO$_2$ advection-diffusion equation to get the value of $u$ and $v$. We demonstrate this method by comparing its result with that from the particle sorting method. [Preview Abstract] |
Tuesday, November 26, 2019 8:24AM - 8:37AM |
Q11.00004: A combined structured planar laser-induced fluorescence (S-PLIF) and particle image velocimetry (S-PIV) method for interfacial and near-wall measurements Victor Voulgaropoulos, Omar Matar, Christos Markides The application of experimental laser-based methods to obtain spatiotemporally resolved information has been emerging as increasingly important in various fields of fluid dynamics, owing to their ability to provide a holistic picture of the phenomena involved and to play a crucial role in benchmarking numerical models. Two-phase systems consisting of fluids with strong variations in their refractive indices in the visible wavelengths, e.g., any gas-liquid system, have, however, been found to compromise traditional laser-based techniques. These optical techniques become susceptible to laser-light refractions and reflections close to the fluid interface, resulting in erroneous interface location and velocity measurements. In this work, we investigate horizontal gas-liquid stratified pipe flows employing a new structured illumination technique. We perform simultaneous structured planar laser-induced fluorescence (S-PLIF) and structured particle image velocimetry (S-PIV) measurements to obtain phase and velocity fields, by minimising total internal reflections effects encountered in traditional PLIF and PIV measurements. The wave characteristics as well as the near-wall and interfacial flow properties are discussed. [Preview Abstract] |
Tuesday, November 26, 2019 8:37AM - 8:50AM |
Q11.00005: Velocity Vector Field Extraction from High Speed Thermograms through Particle Image Velocimetry Tools Guillermo Anaya, Jesus Ortega, Irma Vazquez, Adrian Cederberg, Peter Vorobieff, Clifford Ho Particle Image Velocimetry (PIV) is commonly used to extract velocity from a flow field. While these assessments are usually performed using high-speed visible cameras with tracers, experiments performed at the University of New Mexico generate extensive sets of time-resolved thermograms of a falling hot particle curtain captured at 300 Hz. These sets of data have been analyzed with two commonly used PIV analysis packages, DaVis and PIVlab. The comparison showed consistent velocity fields and contours, along with corresponding velocity correlations as a function of flow position. As expected, the vertical velocity component of these gravity-driven curtains follows a trend that resembles a free-falling sphere rather than a falling sphere experiencing drag. The variation of velocity magnitude displayed negligible variations due to the curtain thickness and/or inlet particle temperature which can be considered negligible for the application. The results obtained will feed the development of a statistical model to estimate the mass flow of a particle curtain using only image-correlation methods. [Preview Abstract] |
Tuesday, November 26, 2019 8:50AM - 9:03AM |
Q11.00006: Experimental study on flow characteristics of vertical upward annular flow boiling in an annulus Joseph Seo, Saya Lee, Daniel Wacker, Junho Lee, Yassin Hassan Hydraulic parameters such as outer and inner film thickness, entrainment rate, droplet deposition rate, and droplet velocity of vertical upward annular flow boiling in an annulus have been measured and studied in the present study. The experiment is performed by observing the annular flow boiling in a vertical annular tube by evaporating refrigerant (hydrofluoroether-7000) with a central heating rod. The outer film thickness is measured using planer laser induced fluorescence (PLIF) with Rhodamine-6G as a fluorescence dye while thickness of inner film which is formed at the surface of the heater is visualized and captured by shadowgraph method. The entrainment rate and deposition rate of droplets are also calculated from the image obtained by shadowgraph. Four high-speed cameras with 3000 fps of frame rate are used. The result of the measurement shows that entrainment and deposition rate of droplets is highly related with not only the wave characteristics on the film but also the onset of burn up at the surface of heating rod which are similar with the results from the studies on annular flow. The set of measurement presented in this study is expected to provide a better understanding and insight of the annular flow boiling phenomena in annuli. [Preview Abstract] |
Tuesday, November 26, 2019 9:03AM - 9:16AM |
Q11.00007: Pressure Field Estimation on Flow over a Sidewall Aneurysm Paulo Yu, Vibhav Durgesh One of the challenges associated with the experimental fluid dynamic study of flow in an aneurysm is the inability to accurately estimate pressure distribution inside the aneurysm sac. The objective of this study is to estimate the pressure field in the sac using velocity data from Particle Image Velocimetry (PIV) measurements. An in-house experimental setup was developed and an idealized sidewall aneurysm was used for this investigation. A computer-controlled pump system was used to precisely control inflow conditions such as Reynolds number (Re) and Womersley number, which ranged from 50-250 and 2-5, respectively. PIV measurements were conducted on a vertical plane inside the aneurysm sac. Proper Orthogonal Decomposition (POD) was used for low-order reconstruction to reduce the noise in the velocity field. The pressure field was estimated numerically using pressure Poisson equation with Neumann boundary conditions. The estimated pressure field in the pipe was compared with a simulated multi-modal solution for a pulsatile flow showing good agreement. The results of the study showed the evolution of the pressure field inside the aneurysm sac and its dependence on change in Reynolds and Womersley numbers. [Preview Abstract] |
Tuesday, November 26, 2019 9:16AM - 9:29AM |
Q11.00008: Feasibility Study on Sparse Processing Particle Image Velocimetry Naoki Kanda, Koki Nankai, Yuji Saito, Taku Nonomura, Keisuke Asai The objective of this study is to investigate accuracy and calculation time of the velocity field data estimated from sparse interrogation area of particle images by Kalman filter and PIV. This estimation method is named sparse processing particle image velocimetry (SPPIV). In this study, the PIV measurement is conducted for NACA0015 under the following conditions; the freestream velocity, the angle of attack, the chord and span of this model were 10 m/s, 16 degree, 100 mm and 300 mm, respectively. Ten proper orthogonal decomposition (POD) modes and five interrogation areas were used and the velocity field was estimated by SPPIV. The optimum location of sparse interrogation area is estimated by greedy method. In this experiment, calculation time of estimating velocity field by SPPIV was approximately 1{\%} of conventional PIV method. In the lowest-order POD mode, the estimated POD mode by SPPIV showed approximately same trend as POD mode calculated by Conventional PIV, however POD mode calculated by SPPIV is sometimes quantitatively different from that calculated by conventional PIV. The quality of particle images and the calculation method of optimum location of sparse interrogation areas should be improved for more accuracy in the future. [Preview Abstract] |
Tuesday, November 26, 2019 9:29AM - 9:42AM |
Q11.00009: Development of experimental visualization method for unsteady hydrodynamic stress field by using photoelasticity of liquid polymer Masakazu Muto, Yoshiyuki Tagawa The experimental visualization for the unsteady hydrodynamic stress field is in demand for the medical field, because the wall shear stress at the inner blood vessel may be the principal cause of the angiopathy. In this study, we develop a visualization method for the hydrodynamic stress field by introducing liquid polymers with photoelastic effects. Photoelasticity is a non-contact optical measurement method based on phase differences obtained by changes in the polarization state of the polymer solution, which results in proportional stress field values. In this experiment, to capture the photoelasticity phenomena at high frame rates, a high-speed polarization camera which contains the array of micro linear polarizers with four incident angles is used. As a result, we can observe an increase of phase difference of the liquid polymers (e.g. xanthan gum and carboxymethyl cellulose) in milli-channel when their flow rate is increased by syringe pump. Furthermore, the sensitivity of phase difference can be changed by the type and the concentration of the polymers. Especially, this method enables us to reveal the area of hydrodynamic stress concentration in the liquid, which other invasive (contact-type) point measurement steady methods may not capture. [Preview Abstract] |
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