Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session A25: Suspensions: General |
Hide Abstracts |
Chair: Srikumar Warrier, Indian Institute Of Technology Madras Room: 251 C |
Sunday, November 24, 2024 8:00AM - 8:13AM |
A25.00001: Heat transfer measurements in sheared neutrally buoyant granular suspension Merin A.P., Vinod Srinivasan Investigating the impact of thermal microconvection on heat transfer in particulate suspensions at low-speed flows is essential for various applications, such as fluidized bed chemical reactors.Our study delves into the complex heat transfer regimes of non-brownian neutrally buoyant suspensions and seeks to examine the effective thermal diffusivity in a suspensions using a specially designed thin gap Taylor-Couette cell. The effective thermal diffusivity is quantified by introducing a thermal pulse to the stationary inner aluminum cylinder and recording the resulting temperature decay on the surface.The research utilizes spherical 1mm polystyrene and 2mm 3D printed PMMA particles in conjunction with a density-matched propylene glycol-glycerol solution to conduct the investigation. PIV imaging employed in comprehending the flow behaviors. Our observations indicate that the Reynolds number emerges as a pivotal determinant in orchestrating the transition from shear-induced diffusion to the onset of inertially driven mixing effects within the suspensions.The study identifies the microscale wakes generated behind particles as pivotal in orchestrating this transition, with the interactions between particle spacing and wake regions yielding a complex relationship for the Nusselt number. Current research unravels the intricate interplay of microconvection, shear-induced diffusion, and inertial mixing in contributing to the enhancement in heat transfer in particulate suspension. |
Sunday, November 24, 2024 8:13AM - 8:26AM |
A25.00002: Abstract Withdrawn
|
Sunday, November 24, 2024 8:26AM - 8:39AM |
A25.00003: All-Printable Liquid Metal Composite Particle Inks Encapsulated with Laponite and PVP Jeongsu Pyeon, Seong-Cheol Huh, Sanghoo Park, Wonho Choe, Hyoungsoo Kim Recently, liquid metal (LM) has emerged as a promising conductive material for next-generation soft and wearable electronics, due to its stretchability, flexibility, and high electrical conductivity. To fully harness this potential, LM electrodes should be coated onto various target substrates using commercial printing techniques. However, printing LM onto flexible substrates for specific purposes is challenging due to the high surface tension, low viscosity, and poor wettability. To resolve these issues, we developed a liquid metal composite particle (LMCP) ink whose viscosity and wettability can be controlled. We believe the LMCP ink can be used in various commercial printing techniques. This LMCP ink features attributes such as coffee-ring-less, crack-less, bilayer-free, and post-processing-less, achieved solely through simple evaporation, while preserving inherent electrical performance. Key strategies include (i) natural sedimentation of LM particles by gravity, (ii) solvent-trapping effect by Laponite during the sedimentation process, and (iii) Marangoni-driven mixing and subsequent sedimentation of LM particles upon evaporation, and (iv) co-assembly of Laponite and PVP on LM particle surfaces, forming LMCP. The resulting LMCP electrodes showed ultra-stretchability (>1200% strain) on diverse substrates and the capability to fabricate complex-shaped patterns through large-area printing methods. Lastly, we will show some useful potential applications during this talk. |
Sunday, November 24, 2024 8:39AM - 8:52AM |
A25.00004: The hydrodynamic interaction of a particle pair sedimenting in a horizontal shear flow Anu Viswanathan Sreekumari Nath, Pijush Patra, Anubhab Roy Collisional dynamics of particles suspended in air have significance in many industrial and natural processes. We calculate the collision rate of a particle pair sedimenting in a simple shear flow where gravity acts in the gradient direction of the simple shear flow. For particles approaching each other in a gaseous medium, continuum lubrication approximation becomes no longer valid, and non-continuum lubrication interactions become important. The Knudsen number, defined as the ratio of the mean free path of the medium to the mean radius of the two interacting spheres, measures the strength of non-continuum effects. Typical pair trajectories for simple shear flow alone or gravity alone are well-studied. We report the non-trivial topology of the pair trajectories for this coupled problem. We evaluate the ideal collision rate as a function of the relative strength of gravity and uniaxial compressional flow and find that it deviates significantly from a linear superposition of these driving terms. By performing trajectory analysis, we show how collision efficiencies vary with the size ratio, the Knudsen number, and the dimensionless parameters capturing the strength of gravity and simple shear flow. |
Sunday, November 24, 2024 8:52AM - 9:05AM |
A25.00005: Collision rates of charged aerosol particles in a linear flow Srikumar Warrier, Pijush Patra, Anubhab Roy Micron-sized charged spheres suspended in air have significance in cloud microphysical processes and influence the droplet size distribution in the cloud. This work studies the collision rate of like-charged dielectric spheres in a linear flow. Depending on the relative size, charges, and separation of the spheres, the electrostatic interaction force between them can be attractive, zero, or repulsive. We calculate the collision rate as a function of the electrostatic force relative to the flow for a range of values of size ratio, charge ratio. We find that polydispersity in terms of particle sizes and charges significantly influences the collision rates. For a charge and size ratio combination for which the near field electrostatics is repulsive, collision is possible below a critical value at which the background flow is strong enough to overcome the electrostatic force. As the electrostatic force increases from zero, we observe two different types of dynamics depending on the size and charge ratio values. In one case, the collision efficiency increases to a maximum and then decreases to zero. In the other case, the collision efficiency decreases monotonically to zero. |
Sunday, November 24, 2024 9:05AM - 9:18AM |
A25.00006: Impact dynamics of suspension droplet on immiscible pool: A closed system study on impact Jamming Boqian Yan, Xiaoyu Tang Impact of suspension droplet on liquid surfaces is important in many applications. The liquid surface provides a different stress distribution as the droplet penetrates compared to impact on solid surfaces, thus probing the suspension response in a transient and inhomogeneous stress condition. When the liquid in the pool is miscible with the suspension droplet, particle migration into the pool reduces the volume fraction, making the analysis challenging. Here, we investigate impact dynamics of cornstarch-in-water droplets on a silicone oil pool, the immiscibility of which ensures the droplet remains a closed system, allowing for probing the jamming transitions and relaxation without external particle loss. We have observed interesting dynamics what differ significantly from those observed with miscible pools and identified the controlling physics of the phenomena. Our findings enhance the common understanding of suspension behaviors under dynamic stress environments. |
Sunday, November 24, 2024 9:18AM - 9:31AM |
A25.00007: Dammed nozzle: clogging of fiber suspensions at constrictions Raaghav Thirumaligai, Justin Maddox, Sreeram Rajesh, Alban Sauret Extruding fiber suspensions from nozzles is important in additive manufacturing to create strong, lightweight materials. However, these complex suspensions present significant fluid mechanics challenges during extrusion. In particular, fibers can clog the nozzle, causing system failures or defects in the final product. In this study, we use model 3D-printed nozzles to control their shapes and opening diameters. Experimentally, we extrude non-Brownian fiber suspensions, varying their volume fraction, length, and diameter, along with the nozzle diameter and suspension flow rate. We systematically characterize the suspension extruded from the nozzle to investigate the probability of nozzle clogging across these parameters. Using the experimental results, we provide some modeling to predict the occurrence of clogs and offer guidelines for optimizing extrusion to prevent nozzle clogging. |
Sunday, November 24, 2024 9:31AM - 9:44AM |
A25.00008: Shear-induced diffusion of rough and frictional particles in concentrated suspensions Han Zhang, Dmitry I Kopelevich, Jason E Butler The shear-induced diffusivity of non-Brownian spheres in viscous, concentrated suspensions was calculated while accounting for particle roughness and friction. The simulation balances lubrication interactions with contact forces which include a normal and tangential component controlled by the roughness and friction coefficient, respectively. The roughness and friction coefficient were varied independently to explore their effects on shear-induced diffusivities. Confirming experiments, roughness reduces diffusivities for concentrated suspensions of frictionless and low-friction particles. However, friction increases the diffusivity and roughened particles have a larger diffusivity at high friction coefficients. The increase of the diffusivity with friction is associated with a significant broadening of the variance of the rotational velocities, while at low friction, the increased roughness promotes organization of the concentrated particles into layered structures aligned in the flow direction. This organization results in a corresponding decrease in the diffusivity for rougher particles. Comparisons of the simulation results with previously published experimental measurements indicate that friction improves the alignment of the results with experiments. |
Sunday, November 24, 2024 9:44AM - 9:57AM |
A25.00009: Electrohydrodynamics-driven pattern formation of liquid drops Asghar Esmaeeli Direct Numerical Simulations are performed to explore the pattern formation of suspension |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2025 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700