Bulletin of the American Physical Society
67th Annual Meeting of the APS Division of Fluid Dynamics
Volume 59, Number 20
Sunday–Tuesday, November 23–25, 2014; San Francisco, California
Session E19: Particle-Laden Flows: General II |
Hide Abstracts |
Chair: Martin Maxey, Brown University Room: 2006 |
Sunday, November 23, 2014 4:45PM - 4:58PM |
E19.00001: Deformation regimes for immersed single particle collisions Angel Ruiz-Angulo, Melany Hunt This work presents experimental measurements of the approach and rebound of single particles colliding with a ``deformable'' surface in a viscous liquid. The complex interaction between the fluid and the solid phases is coupled through the dynamics of the flow as well as the deformation process. A simple pendulum experiment was used to produced single controlled collisions; steel particles were used to impact different aluminum alloy samples in different aqueous mixtures of glycerol and water as a viscous fluid. For the combination of materials proposed, the elastic limit is reached at relatively low velocities. The deformations produced by the collision were analyzed using an optical profilometer. The measurements showed that the size of the indentations is independent of the fluid media. It was found that the size of the indentations was the same for collisions in air than for the rest of the collisions using various viscous fluids. [Preview Abstract] |
Sunday, November 23, 2014 4:58PM - 5:11PM |
E19.00002: Particle-laden thin film flow with surface tension Li Wang, Aliki Mavromoustaki, Andrea Bertozzi We derive a dynamic model which describes the evolution of a thin film, laden with negatively buoyant particles on an incline including the surface tension effect. The original model (Murisic et. al [J. Fluid Mech. 2013]) that only considers the leading order effects such as gravity and shear induced migration can produce singular shock when the particle concentration is above a critical value. Our model builds on a similar equilibrium theory and results in a $2\times 2$ system of conservation laws augmented with forth order diffusion. Such diffusion is both a stand-alone regularization and a modification of the original flux, thus posing challenges for both the design of numerical schemes and analysis. We present the model and a proposed numerical method that produces solutions in which the singularity is suppressed, leading to more physical solutions. [Preview Abstract] |
Sunday, November 23, 2014 5:11PM - 5:24PM |
E19.00003: Dynamics of particle migration in a channel flow of viscoelastic fluids Gaojin Li, Gareth McKinley, Arezoo Ardekani Understanding the dynamics of particle transport in channel flows is important for many problems related to industrial, environmental and biological applications. Cross streamline migration of particles due to inertial and/or viscoelastic effects has been studied and utilized for particle focusing, particle separation and fluid mixing in microfluidic devices. Most previous studies on viscoelastic-induced particle focusing are limited to low Reynolds number flows and some of the mechanisms leading to particle migration remain unclear. In this work, we numerically study the interio-elastic migration of particles in a microfluidic channel flow driven by a constant pressure gradient. Simulations cover the following range of parameters: Reynolds numbers 4 $\le $ Re $\le $ 100, Weissenberg numbers 0 $\le $ Wi $\le $ 2, for weakly viscoelastic fluids with elasticity numbers 0 $\le $ El$=$ Wi/Re $\le $ 0.2. Both viscoelasticity and shear-thinning effects are considered. The competition between inertia and viscoelasticity leads to different equilibrium particle positions between the channel centerline and the wall. The equilibrium position moves towards the centerline at higher El for a given Reynolds number due to the dominance of the cross-streamline viscoelastic force compared to the inertial lift. Shear-thinning effects increase the effective shear rate, and consequently, the dominance of the inertial lift drives the particle towards the wall. [Preview Abstract] |
Sunday, November 23, 2014 5:24PM - 5:37PM |
E19.00004: Dispersion of a suspension plug in oscillatory pressure-driven flow Francis Cui, Amanda Howard, Martin Maxey, Anubhav Tripathi We investigate the dispersion of suspension plugs in a micro-capillary as they are sheared in periodic pressure-driven flows. To study this novel configuration, a new experimental method was implemented to observe the shear-induced evolution of semi-infinite suspension plugs consisting of non-colloidal spherical particles (90-$\mu$m mean diameter) at dilute and high concentrations for various values of applied strain. In this cyclic shearing flow, irreversible particle migration arises from numerous unpredictable hydrodynamic interactions between particles and walls. Although the periodic velocity profiles do not lead to any significant increase in plug length, significant streamwise particle migration was observed near the walls of the capillary, becoming more pronounced with increasing strain amplitude $\gamma_0$. This experimental outcome agrees with the results of numerical simulation, which produces analogous behavior for a suspension sheared between parallel walls. Calculating dimensionless particle diffusivities $D_z$ for various $\gamma_0$ allows us to determine a cutoff point demarcating regimes of reversibility and irreversibility. [Preview Abstract] |
Sunday, November 23, 2014 5:37PM - 5:50PM |
E19.00005: Shock propagation over a deformable particle Thomas Jackson, Prashanth Sridharan, Ju Zhang, Siva Balachandar The interaction of strong shock waves with a deformable particle is an important fundamental problem in applications of multiphase flow; e.g., volcanic blasts, shock past a bubble, or explosives loaded with particles. In these applications the shock strength is greater than the yield strength of the particles, and as a result the particles will move and deform. We consider the impedance and shock-speed ratios, which define the nature of the deformation, for a variety of materials. Understanding the dynamic behavior of isolated particles at the microscale is important for developing point-particle models at the macroscale. Numerical results will be presented using the axisymmetric assumption to reduce computational costs. For a variety of shock strengths, we plot as a function of time a number of quantities, such as maximum particle temperature and pressure, mass integrated temperature and pressure, particle position. We also show results for non-spherical particles to determine the effect of particle shape. Here, we consider an ellipsoid align along or normal to the flow direction. Finally, preliminary results using a fully 3-D code will be presented. [Preview Abstract] |
Sunday, November 23, 2014 5:50PM - 6:03PM |
E19.00006: Shock-particle cloud interaction: Isolated unsteadiness contributions from shock and vortical structures Zahra Hosseinzadeh-Nik, Jonathan D. Regele The interaction between shock waves and particles in a multiphase shock tube is an efficient way to study dense compressible particle-laden flows. However, it is difficult to study the interaction between the two phases at the particle scale. Recent numerical simulations [Regele {\it et al.}, Int. J. Multiphase Flow {\bf 61}, 1-13 (2014)] show that after a shock wave impacts a particle cloud strong unsteady effects exist inside and in the wake immediately behind the cloud. This unsteadiness is attributed to the fluctuation associated with vortical structures and reverberating compression wave radiation. It is still unclear how the unsteady flow behavior is partitioned between vortical structures and reverberating finite disturbances. In this work numerical simulations are performed that attempt to replicate the unsteady wake behavior for the same mean flow conditions that are observed after a shock wave passage without using a shock wave to initialize the flow. The results are volume-averaged to compare the unsteady velocity magnitude with that of the previous results to determine the contribution from vortical unsteadiness. [Preview Abstract] |
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. |
© 2024 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