Front Tracking Simulation of a Liquid Capsule Enclosed by an Elastic Membrane

Abstract

Dynamics of a liquid capsule enclosed by an elastic membrane in a shear flow is investigated using front tracking finite difference method. We compute deformation, orientation and tank treading, as functions of forcing (capillary number) and viscosity ratio for two different membrane constitutive equations—Neo-Hookean and Skalak. The computed results compare very well with those obtained by high-order Boundary element methods as well as small deformation perturbation analysis. The simulation shows that a drop and a capsule, even under those circumstances that result in the same Taylor deformation criterion for both, attain very different shapes. The tank-treading period even for different capillary numbers as well as capsules with different constitutive laws, is determined by the deformation and the viscosity ratio.