Nonlinear dynamics of a microswimmer in Poiseuille flow

TL;DR

This paper investigates the complex three-dimensional motion of spherical microswimmers in cylindrical Poiseuille flow, revealing stable trajectories influenced by hydrodynamic interactions, with implications for understanding microscale fluid dynamics.

Contribution

It introduces a Hamiltonian mapping of microswimmer dynamics in flow, identifying stable trajectories and effects of hydrodynamic interactions for different swimmer types.

Findings

Swinging and tumbling trajectories identified

Hydrodynamic interactions lead to stable, distinct trajectories

Differences observed between puller and pusher swimmers

Abstract

We study the three-dimensional dynamics of a spherical microswimmer in cylindrical Poiseuille flow which can be mapped onto a Hamiltonian system. Swinging and tumbling trajectories are identified. In 2D they are equivalent to oscillating and circling solutions of a mathematical pendulum. Hydrodynamic interactions between the swimmer and confining channel walls lead to dissipative dynamics and result in stable trajectories, different for pullers and pushers. We demonstrate this behavior in the dipole approximation of the swimmer and with simulations using the method of multi-particle collision dynamics.