Rheology of a concentrated suspension of spherical squirmers: Monolayer in simple shear flow

Abstract

A concentrated, vertical monolayer of identical spherical squirmers, which may be bottom heavy, and which are subjected to a linear shear flow, is modelled computationally by two different methods: Stokesian dynamics, and a lubrication-theory-based method. Inertia is negligible. The aim is to compute the effective shear viscosity and, where possible, the normal stress differences as functions of the areal fraction of spheres, the squirming parameter (proportional to the ratio of a squirmer's active stresslet to its swimming speed), the ratio of swimming speed to a typical speed of the shear flow, the bottom-heaviness parameter, the angle that the shear flow makes with the horizontal and two ..