Lattice-Boltzmann Hydrodynamics of Anisotropic Active Matter

TL;DR

This paper presents a lattice-Boltzmann simulation method for anisotropic active particles, revealing how shape influences hydrodynamic multipole moments and swimmer behavior in confined environments.

Contribution

It introduces a novel simulation approach for anisotropic active matter with hydrodynamics, including higher-order multipole characterization.

Findings

Shape anisotropy induces strong quadrupole and octupole moments.

Hydrodynamic interactions depend on particle shape and influence collective behavior.

The method enables detailed study of swimmer dynamics in complex geometries.

Abstract

A plethora of active matter models exist that describe the behavior of self-propelled particles (or swimmers), both with and without hydrodynamics. However, there are few studies that consider shape-anisotropic swimmers and include hydrodynamic interactions. Here, we introduce a simple method to simulate self-propelled colloids interacting hydrodynamically in a viscous medium using the lattice-Boltzmann technique. Our model is based on raspberry-type viscous coupling and a force/counter-force formalism which ensures that the system is force free. We consider several anisotropic shapes and characterize their hydrodynamic multipolar flow field. We demonstrate that shape-anisotropy can lead to the presence of a strong quadrupole and octupole moments, in addition to the principle dipole moment. The ability to simulate and characterize these higher-order moments will prove crucial for understanding the behavior of model swimmers in confining geometries.