Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session B18: Fluids II |
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Sponsoring Units: DFD Chair: Muralikrishnan Gopalakrishnan Meena, Oak Ridge National Laboratory Room: Room 210 |
Monday, March 6, 2023 11:30AM - 11:42AM |
B18.00001: The Effect of Size Polydispersity of Graphene Oxide on its Solution Dispersity and Rheological Properties Eun Ho Cho, So Youn Kim Graphene oxide (GO) has been considered a promising material that could be employed in advanced materials science and engineering due to its outstanding mechanical and electrical properties. Noting the application of GO is initiated from the GO in solution, a fundamental understanding of GO dispersions as colloids should proceed to control the properties of GO-based application. Among many parameters determining the state of colloidal dispersion, the size and its distribution should be firstly considered, which ultimately determines the final physical properties. For example, the bidispersed GO in size is known to improve the electrical property compared to the monodisperse GO. The result awakens the importance of the size distribution of GO size again, requiring more systematic studies on the GO dispersions with precise control of the polydispersity. |
Monday, March 6, 2023 11:42AM - 11:54AM |
B18.00002: Influence of Polymer Architecture on Extensional Solution Flow Adam Linscott, Lauren Hong, Madison Castellanos, Svetlana Morozova Solution flows are a critical component in our understanding of spray applications and biological functions. Drop-on-substrate rheology (DOSR) offers strong insights into the fluid dynamics of non-Newtonian droplet breakup. Polymers, when combined in solution, play a stabilizing role during the droplet breakup process as a result of their elasticity. By modifying the architecture of a linear polymer backbone, these elastic contributions can be altered to significantly influence solution flow properties. We have studied the extensional flow behaviors of both graft and liquid-crystalline polymers with DOSR as each species exhibits unique architectures of varying degrees of backbone linearization and dissymmetries between monomer subunits. Namely, we have focused on grafting methoxy polyethylene glycol amine onto hydrolyzed polyacrylamide at various grafting densities. Changes in size scale were then confirmed via light scattering and viscometry. Finally, the relaxation times of graft polymer in solution were compared to liquid crystal flows to understand the full spectrum of the effect of backbone flexibility. |
Monday, March 6, 2023 11:54AM - 12:06PM |
B18.00003: Rheology of particle suspensions in viscoelastic fluids Carina Martinez, Chao Wang, Hao Sun, Divya Iyer, Samanvaya Srivastava, Vivek Sharma The extensional rheology response of suspensions in viscoelastic fluids and the influence of matrix viscoelasticity on suspended particle dynamics remain less well-understood. Many formulations, including paints, coatings, cosmetics, foodstuff, and biological fluids, form examples of suspensions in viscoelastic fluid. This contribution contrasts the response of particle-laden solutions prepared with colloidal silica particles in two viscoelastic fluid systems based on polyethylene oxide and 2-hydroxyethyl cellulose. A strikingly distinct response was found in both shear and extensional flows characterized using torsional rheometry and capillarity-driven extensional flows using DoS rheometry, respectively. We present the visualization and analysis of pinching dynamics and rheology of particle suspensions, systematically comparing the dilute solution response to existing theoretical models. We elucidate the influence of polymer-particle interactions and macromolecular properties of the suspending fluid on the rheology and pinching dynamics and discuss the implications for dispensing macromolecular complex fluids. |
Monday, March 6, 2023 12:06PM - 12:18PM |
B18.00004: Stringiness, stretching and pinching behavior of formulations Vihar Trada, Karthika Suresh, Cheryl L Slykas, Jan Raphael Sagun, Vivek Sharma In this contribution, we analyze the stretching and pinching behavior of various model fluids using dripping, dripping-onto-substrate rheometry, and a home-built stretching device that applies constant stretch velocity. We chase after the influence of surface tension, non-Newtonian rate-dependent viscosity, and elasticity, especially for multicomponent formulations. The experiments rely on high-speed visualization and quantitative analysis of pinching dynamics, supplemented by shear rheology studies. |
Monday, March 6, 2023 12:18PM - 12:30PM |
B18.00005: How swelling affects hydrogel surface wettability Amir Kashani, H. Jeremy J Cho Wetting behavior of hydrogels can be highly time dependent. Some studies have suggested that this time dependence is due to the water content in swollen hydrogels affecting surface properties. We investigate how this time dependence is related to the diffusion of water into the gel from the droplet. We performed time-dependent advancing and receding contact angle experiments with hydrogels of various thicknesses where we expect thicker gels to have longer time constants in their contact angle evolution. In addition, we tested whether there is a dependency of crosslinking on the time constant. The results of this study will help us to better understand problems in controlling hydrogel surface wettability and how changing involved variables in preparing gels, would improve our knowledge of hydrophilic soft materials. |
Monday, March 6, 2023 12:30PM - 12:42PM |
B18.00006: Directed droplet migration along thin fibers Hamza K Khattak, Aileen Shanzeela, Kari Dalnoki-Veress Small droplets can spontaneously move on conical fibers to minimize the surface energy of the system. This is a feature used by cacti, and other plants, to harvest water from the air. Similar ideas are being developed to carry out fog harvesting in arid regions of the globe. Here we investigate a similar concept: propelling droplets with two fibers. We deposit micrometric droplets between pairs of thin fibers. By controlling the angle between the fibers, we can direct the motion of the droplets. We find that droplets spontaneously move towards the apex of the angled fibers. The speed of the droplet motion increases both with the angle between the fibers and the distance the droplet spans across the fibers. |
Monday, March 6, 2023 12:42PM - 12:54PM |
B18.00007: Coalescence of isotropic and nematic droplets in quasi 2D liquid crystal films Christoph Klopp, Alexey Eremin, Ralf Stannarius
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Monday, March 6, 2023 12:54PM - 1:06PM |
B18.00008: A hydrodynamic analog of the Aharanov-Bohm effect Kyle I McKee, Valeri Frumkin, John W Bush A millimetric droplet may self-propel on the surface of a vibrating bath through a resonant interaction with its own wave field. The droplet and wave comprise a classical realization of wave-particle duality, a feature once thought to be unique to the quantum realm. The walking droplet (or `walker') system has been used to achieve hydrodynamic analogs of a number of canonical quantum effects. Here, we use it to develop and explore an analog to the Aharonov-Bohm (AB) effect, as has been a point of contention in the physics community since its discovery in 1959. The controversy surrounds the interpretation of vector potentials in quantum mechanics; specifically, are they fundamental physical objects or mathematical abstractions? In classical mechanics, only derivatives of potentials(specifically, fields) influence observable physics while, in quantum mechanics, the AB effect predicts interference effects even when all fields are zero. In our experiments, a walker is confined to an annular channel, inside which a submerged rotating disk creates a localized region of vorticity. Although the droplet does not interact directly with the vortex, its wave-field does. We examine how both the wave field and drop motion are altered by the vortex, and connect the observed behavior to the AB effect. |
Monday, March 6, 2023 1:06PM - 1:18PM |
B18.00009: A hydrodynamic analog of the Kapitza-Dirac effect Bauyrzhan K Primkulov, Valeri Frumkin, Pedro J Saenz, John W Bush In 1933, Kapitza and Dirac predicted that a standing wave of light would diffract a beam of electrons—an effect experimentally confirmed only after the advent of lasers. In 2005, Couder and Fort discovered that millimetric droplets can self-propel along the surface of a vibrating liquid bath, guided by their own pilot-wave field. These walking droplets represent a macroscopic realization of wave-particle duality and have been shown to exhibit many features previously thought to be exclusive to the subatomic, quantum realm. We here examine a hydrodynamic analog of the Kapitza-Dirac effect through consideration of walking droplets interacting with a localized beam of standing Faraday waves, which is conditioned using submerged features in the liquid bath. |
Monday, March 6, 2023 1:18PM - 1:30PM |
B18.00010: New Insights and Phase Diagram into Achieving Monodispersity in Microfluidic Generated Drops Dheeraj Sapkota, Laura L Adams
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Monday, March 6, 2023 1:30PM - 1:42PM |
B18.00011: Step into the Ring: the role of particle shape on deposition patterns in dense drying droplets Brian C Seper, Sam Nielsen, Michelle R Driscoll Sessile droplets of colloidal suspensions display a diverse range of phenomena when they dry, and one of the most common of these are the ring stains from spilled drops of coffee on your countertop. This occurs because a radial fluid flow is induced by strong evaporation at the pinned edge of the droplet. This flow transports suspended particles to the edge of the droplet yielding the ring pattern seen upon drying. Many factors can influence the final dried pattern such as evaporation kinetics, surface wetting, colloidal interactions, particle anisotropy, and the volume fraction of the suspension. Due to the challenge of synthesizing rod shaped particles, much less attention has been given to investigating how rod particulate suspensions compare with their spherical counterparts, and initial studies suggested that suspensions with rod shaped particles would not form ring patterns upon drying at all. Here we present a broad experimental study of the dynamics and morphology of sessile dried deposits for silica particles suspended in water with aspect ratios varying from 1 to 11 and volume fractions ranging from 0.01 to 0.4. We observe that a ring deposition forms for all particle aspect ratios at low concentrations. In general, we find that the final dried pattern, quantified using both microscopy and optical profilometry, is controlled both by the concentration of the suspension and the aspect ratio of the colloids present in the suspension. |
Monday, March 6, 2023 1:42PM - 1:54PM |
B18.00012: Droplet release and fragmentation of onion cutting Zixuan Wu, Alireza Hooshanginejad, Weilun Wang, Sunghwan Jung Cutting onions in kitchen often results in tear induction due to the generation and advection of pungent aerosols. In this talk, we explore the correlations between onion tissue straining and the droplet ejection mechanisms during a cutting sequence under various onion-blade features and interactions. Complexity of droplets ejection in onions originates in the soft mesophyll tissues, effectively functioning as a collection of pressurized elastic capsules, sandwiched by tough epidermal skins, allowing for localized stress concentration before skin rupture. We extract the size and speed (up to 30 m/s) distribution of droplets ejecting from fractured onion surface for different blade thicknesses, cutting speeds, and onion orientations. We applied Digital Image Correlation to reveal the 2D stress map of the transverse plane upon indentation, rupture, and steady-state cutting. We further developed direct pressure probing methodology to determine the tissue pressure during cutting. The current study helps establish connections between contact mechanics of pressurized elastic composites and fluid physics of droplet fragmentations, specifically revealing insights on the "tearless" cutting techniques for onions. |
Monday, March 6, 2023 1:54PM - 2:06PM |
B18.00013: Active Brownian Particles in a disordered motility environment Davide Breoni, Hartmut Löwen, Gianni Jacucci, Giorgio Volpe, Sylvain Gigan The study of active matter, i.e. matter that consumes energy to perform actions, is fundamental to deepen the knowledge of living systems, as for example bacterial colonies or flocks of birds, and their collective behaviors. Complex environments, like the internal structure of a cell or a blood vessel, are of particular relevance in this field, as they provide a better description of the real-life settings typical of living matter. |
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