Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T11: Flow of Complex Fluids, Rheology Structures and Instabilities IIRecordings Available
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Sponsoring Units: DFD Chair: Manish Kumar, Purdue Room: McCormick Place W-181B |
Thursday, March 17, 2022 11:30AM - 11:42AM |
T11.00001: Tristability in confined viscoelastic flow Manish Kumar, Arezoo M Ardekani Viscoelastic flows through confined geometries are relevant in enhanced oil recovery, microbial mining, environmental remediation, and targeted drug delivery. The confinement induces large elastic stresses in viscoelastic flow, which leads to purely elastic instability of the flow. We have numerically investigated viscoelastic instabilities between two cylinders located in the streamwise direction in a channel. We have discovered the tristability of the flow states in the region between the cylinders induced by the formation of streaks characterized by high polymeric stress. The streaks formed by high polymeric stress act as a barrier for the flow crossing the regions, which leads to flow separation and the formation of multiple flow states inside the channel. We have investigated the criteria of viscoelastic instability and discovered that the criterion of purely elastic instability can be used to forecast the type and location of instability after the transition. We also explored the effect of fluid rheology and cylinders’ size and separation on the flow instabilities. |
Thursday, March 17, 2022 11:42AM - 11:54AM |
T11.00002: Boundary layer flow of Carbopol gel modeled as a Herschel-Bulkley fluid around a moving plate NDRI A KONAN, Eilis Rosenbaum, Mehrdad Massoudi Wellbore cementing operations are mostly aimed at isolating wells from the invasion and migration of surrounding fluid from the formation, as well as supporting the steel pipe casing in the well center. Cementing consists of pumping cement slurry down to the bottom of the wells, under high pressures through the casing and into the annulus space between the casing and the formation. This results in the slurry flowing upward along the solid boundaries of the formation and the casing, and subsequently filling the space between the actual wellbore and the casing. Cement slurries are yield stress fluids with the yield stress dependent on the shear rate, concentration of cement particles, etc. [see Banfill, 2006]. They exhibit thixotropy, which can be modeled through a dependence of the viscous stress on a structural parameter describing the aggregation degree [Tao et al., 2020]. A less complex problem, related to the flow of a cement slurry along the solid boundaries of the wellbore and the casing, is the flow of a non-thixotropic Carbopol gel which exhibits uniform thickness boundary layer along a moving plate plunged into the gel. This was experimentally studied by Boujlel et al., (2012) and detailed velocity profiles from PIV measurements were provided. We model the Carbopol gel solution as a Herschel-Bulkley visco-plastic fluid. The numerical solutions are calculated by relying on the regularization methods where a singular viscosity at zero strain rate is approximated with a viscosity form dependent on a small parameter and expected to converge to the viscosity at the limit of zero strain [Frigaard & Nouar, 2005]. The methods are implemented as customized non-Newtonian viscosity libraries and solved along with the governing equations in the open-source toolbox/library, OpenFOAM. The results show that the boundary layer thickness is satisfactorily predicted against Boujlel et al., (2012) measurements, along with the fluid recirculation exhibited by the PIV. |
Thursday, March 17, 2022 11:54AM - 12:06PM |
T11.00003: Keeping Our Sheet Together: Dynamics and Fragmentation in Yield-Stress Fluid Sheets Carly E Galvin, Brendan C Blackwell, Michelle R Driscoll The two-dimensional geometry of an expanding fluid sheet presents a unique opportunity to explore material instabilities. The behavior of these sheets and the ways in which they fragment have been examined for several centuries, but the vast majority of this research has centered around Newtonian fluids. We are working toward an analogous understanding of complex fluid sheets, focusing specifically on yield-stress fluids. In our experiments, we generate the sheets via the collision of two liquid jets and film their dynamics using high-speed photography; the behavior of the sheet is set by the rheology of the fluid and the velocity of the impinging jets. Our findings indicate that quickly-expanding sheets (created by faster jets) are less stable than slowly flowing sheets. We will show that fragmentation can be categorized into different regimes based on jet velocity, jet diameter, and concentration of polymer. Furthermore, we use a suite of different fluids to determine which fluid parameters—such as yield stress, infinite-shear viscosity, surface tension, and elasticity—control the stability of the sheet. |
Thursday, March 17, 2022 12:06PM - 12:18PM |
T11.00004: Dynamics of bubbles induced by multiple femtosecond laser pulses D Chaitanya K Rao, Veena S Mooss, Yogeshwar N Mishra, Dag Hanstorp Femtosecond laser pulse interaction with transparent materials has captivated much attention in recent years. Nonlinear interaction of focused femtosecond laser pulses in liquids offer means for the micromachining of bulk materials and an accurate laser tool for photo disruptive surgery in tissues. Femtosecond laser-induced plasma in liquids results in filamentation and subsequent formation of bubbles. In the present work, high-speed imaging is used to reveal the Spatio-temporal evolution and interaction of these bubbles as a function of laser pulse energy (∼25 to 800 µJ), liquid medium (water, ethanol, and glycerol), and focusing optics (with and without spherical aberrations). The influence of the train of laser pulses of different energy on the filament length and size distribution of bubbles is discussed in detail. The introduction of multiple pulses leads to a strong interaction between the bubbles and controls the lifetime of the existing bubbles and the creation of new bubbles, thereby increasing the population and size of the bubbles. The incident laser energy and pulse width employed in this work can be advantageous in diverse industrial applications such as surface cleaning, microelectronics, and can be useful for medical procedures such as intraocular microsurgery. |
Thursday, March 17, 2022 12:18PM - 12:30PM |
T11.00005: Dimples and Voids in Dense Drying Drops Brian C Seper, Srishti Arora, Max Paik, Michelle R Driscoll Despite their simple appearance, sessile droplets of colloidal suspensions display a diverse range of phenomena when they dry, from ring depositions to a variety of mechanical instabilities. A multiplicity of factors can influence the final dried pattern such as evaporation kinetics, surface chemistry, colloidal interactions, particle anisotropy, and the volume fraction of the suspension. We observe a novel "Dimple-Void" instability in dense drying suspension drops; this instability appears when the colloidal volume is at and above 30 percent of the drop volume and forms on the order of tens of milliseconds. Here we present an experimental study of the dynamics and morphology of this instability using high-resolution, high-speed imaging and profilometry, and show how the colloidal particle size as well as material affects the dynamics of this system. |
Thursday, March 17, 2022 12:30PM - 12:42PM |
T11.00006: Surface tension of cavitation bubbles Marine Bossert, Etienne Rolley, Isabelle Trimaille, Pierre-Etienne WOLF, Panayotis Spathis, Laurent Cagnon Cavitation occurs in porous materials when pores are connected to the outer gas reservoir by small constrictions. We have developed a simple technique to obtain such ink-bottle pores in monolithic porous silicon and porous alumina membranes. When the pore diameter is larger than about 10 nm, such materials empty through homogeneous cavitation, as recently demonstrated using hexane at room temperature1. |
Thursday, March 17, 2022 12:42PM - 12:54PM |
T11.00007: Observation of bubble growth in evaporating polymeric droplets via skin formation Gannena K S Raghuram, Chaitanya Kumar Rao, Durbar Roy, Aloke Kumar, Saptarshi Basu We report the observation of bubble formation, growth, and different modes of rupture/breakup in isolated evaporating polymeric droplets. The accumulation of polymer at the droplet surface leads to bubble formation, growth, and subsequent breakup of the evaporating droplet. At high heating rates and for low concentrations of polymer, uninterrupted evaporation of droplets occurs while bubble growth and breakup at droplet surface occur for high polymeric concentration droplets. In contrast, rapid bubble growth from the droplet center is initiated for solutions with high polymer concentration under low heating rates. The bubble growth in droplets occurs due to skin formation following the accumulation of polymer during the evaporation process. The polymer concentration and temperature profiles of droplets for different heating rates are obtained numerically. The numerically obtained timescales for skin layer formation agree well with the experimental bubble ejection timescales. |
Thursday, March 17, 2022 12:54PM - 1:06PM |
T11.00008: How a mass-transfer balance controls surfactant-enhanced boiling Mario R Mata Arenales, Brandon Ortiz, Han-Jae J Cho Boiling is ubiquitous and improvements to boiling performance are challenging due to the unpredictable nature of bubble behavior. One way to improve boiling is through surfactants, which alter the solid-liquid and liquid-vapor interfacial properties of water. Previous studies have found that heat transfer enhancement increases with surfactant concentration, concomitant with surfactant micellization. However, there may be a universal concentration of heat transfer enhancement not associated with micellization across a wide range of nonionic, anionic, and cationic surfactants. We hypothesize that this universal concentration is dictated by a balance of the advection of surfactants in bulk solution and the departure of surfactants adsorbed to bubble interfaces. The results of this work could ultimately pave the way towards simpler and more economical solutions to improve two-phase heat transfer processes. |
Thursday, March 17, 2022 1:06PM - 1:18PM |
T11.00009: Axisymmetric Bubble Growth and Detachment Subject to Inhomogeneous Magnetic Fields in Microgravity Alvaro Romero Calvo, Miguel Herrada, Gabriel Cano-Gómez, Hanspeter Schaub Understanding interfacial flows in microgravity is essential for space technologies such as water electrolysis or boiling. The use of magnetic polarization forces has been recently proposed to control bubble flows, whose magnetic susceptibility may be increased by employing ferrofluids. This paper introduces a numerical interface-tracking model addressing the growth and detachment of axisymmetric gas bubbles when subject to inhomogeneous magnetic fields in microgravity. A fully coupled ferrohydrodynamic framework of analysis is implemented using an efficient monolithic approach and second-order finite differences. The equilibrium, global stability, and modal response of axisymmetric bubbles within ferrofluids are studied. In particular, the shape and departure volume of the bubble under different fluid-magnetic configurations is addressed, offering key insights into this problem and paving the path for the development of novel space applications. |
Thursday, March 17, 2022 1:18PM - 1:30PM |
T11.00010: Dynamical surface fluctuations of a contaminated microbubble Li Shen, Marco De Corato We investigate the dynamical surface fluctuations of a surfactant-laden and surface viscous microbubble. Particular cases of a free system and that of micrometric particles where a time-dependent periodic forcing force is exerted at its poles are examined as well as more general forcing mechanisms such as magnetic, electric or acoustic fields. Assuming a small-amplitude approximation in the surface fluctuations, the effect of bulk viscosity is neglected and assuming the forcing are point particles, analytical expressions are derived for the dynamic fluctuations of the interface. The damping effect of surface viscosity and soluto-Marangoni fields on surface fluctuations is studied with the modified wave dispersion. This is a first step in characterising the interfacial fluctuations of a microbubble more systematically, under different levels of surface contamination. |
Thursday, March 17, 2022 1:30PM - 1:42PM |
T11.00011: Modeling Induced-Charge Electroosmosis using a meso-scale approach J. Galen Wang, Daniel R Ladiges, Ishan Srivastava, Andrew J Nonaka, John B Bell, Sean P Carney, Alejandro L Garcia, Aleksander Donev Electrokinetic flows are important in many applications such as microfluidic pumping and desalination. We recently developed a meso-scale fluid model, the Discrete-Ion Stochastic Continuum Overdamped Solvent (DISCOS) algorithm, to study non-linear electrokinetic effect such as induced-charge electroosmosis (ICEO). ICEO is specifically interesting because it can generate steady flow in an AC field. Electrokinetic effect is inherently related to the development of the electric double layers due to fluctuations of ions in an electrolyte solution, where molecular-scale physics that cannot be captured by a continuum model are still important. While molecular dynamics can also model the double layer, it is computationally expensive and is challenging to scale the problem size to real applications. To overcome these challenges, we simulate ICEO over a metallic plate in DISCOS, where solvent is modeled under the fluctuating hydrodynamics framework, and the ions are treated by the immersed boundary method. We compare our results to experiments and theories with electric field generating ζ-potentials on the order of the thermal voltage, and we obtain qualitative agreement. We also extend electric fields beyond this parameter space, and several interesting remarks are made in this regime. |
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