A Multiscale Numerical Simulation of Quasi-Two-Dimensional Bacterial Turbulence Using a Regularized Stokeslet Representation

Abstract

Self-propelled particles in low-Reynolds-number flow interact through the surrounding fluid. This study examined the collective dynamics of model bacterial swimmers in which a collection of regularized Stokeslets and rotlets captured their surrounding near-field flow. With the hydrodynamic and steric repulsive interactions, the numerical simulation of the swimming cells in a two-dimensional plane reproduced well-known turbulence-like dynamics, characterized by coherent collective vortex dynamics, agreeing with the previous. Furthermore, we incorporated two parallel free-slip boundaries to consider the impact of geometrical confinement. We observed that the size of the vortices of bacterial turbulence attained its maximal value when the width of the two boundaries was of the same order as the swimmer length. The rotlet term induces chiral swimming trajectories in the presence of confines for a dilute suspension. In a dense turbulence suspension, however, we observed that the chiral dynamics are subdued.