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DY: Fachverband Dynamik und Statistische Physik

DY 30: Complex Fluids and Soft Matter 1 - organized by Uwe Thiele (Münster) (joint session DY/CPP)

DY 30.4: Talk

Tuesday, March 23, 2021, 15:30–15:50, DYc

Hydrodynamics of a Pair of Soft Capsules in Inertial Microfluidics — •Kuntal Patel and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, Berlin, Germany

In recent years, inertial microfluidics has emerged as a robust technique to precisely manipulate solid particles and biological cells. Also, the fact that inertial microfluidics operates at finite Reynolds numbers enables to achieve high throughput. In the present work, we perform 3D numerical simulations to study the hydrodynamic interaction and inertial migration of two soft capsules in a microchannel with quadratic cross section. We employ the lattice Boltzmann method to determine fluid flow and the finite element method to model capsule dynamics. The coupling between bulk fluid and capsules is realized using the immersed boundary method.

We investigate the effect of different starting positions for mono- and bi-dispersed pairs of varying softness and capsule shape. Based on the temporal evolution of interparticle distance, we characterize the dynamics of various mono- and bi-dispersed pairs into four types: stable pair, stable pair with damped oscillations, stable pair with bounded oscillations, and unstable pair. We observe that stable pairs become unstable when increasing the particle stiffness. Furthermore, a pair with both capsules in the same channel half is more prone to become unstable than a pair with capsules in the opposite channel halves.