Chirotactic response of microswimmers in fluids with odd viscosity

TL;DR

This paper investigates how microswimmers behave in fluids with odd viscosity, revealing unique orientational dynamics and chirotaxis behaviors influenced by the fluid's chiral properties.

Contribution

It provides an exact solution for flow around rotating bodies in odd viscosity fluids and analyzes the resulting microswimmer orientation dynamics.

Findings

Force-dipole swimmers precess around the axis

Pushers exhibit bimodal chirotaxis

Pullers orbit perpendicular to the axis

Abstract

Odd viscosity is a property of chiral active fluids with broken time-reversal and parity symmetries. We show that the flow of such a fluid around a rotating axisymmetric body is exactly solvable and use this solution to determine the orientational dynamics of surface-driven microswimmers. Swimmers with a force-dipole moment exhibit precession around the axis of the odd viscosity. In addition, pushers show bimodal chirotaxis, i.e., alignment parallel or antiparallel to the axis, while pullers orbit in a plane perpendicular to it. A chiral swimmer that itself has a broken parity symmetry can exhibit unimodal chirotaxis and always align in the same direction.