Pursuit and Synchronization in Hydrodynamic Dipoles

TL;DR

This paper theoretically investigates the dynamics of hydrodynamic dipoles in confined microfluidic environments, revealing stable pursuit and synchronization behaviors among swimmer pairs, which influence collective microswimmer behavior.

Contribution

It introduces a theoretical framework for asymmetric swimmer interactions in confined geometries, identifying stable pursuit and synchronization modes based on swimmer shape.

Findings

Pursuit mode is stable for large tail swimmers.

Synchronization mode is stable for large head swimmers.

Results impact understanding of collective microswimmer behavior.

Abstract

We study theoretically the behavior of a class of hydrodynamic dipoles. This study is motivated by recent experiments on synthetic and biological swimmers in microfluidic \textit{Hele-Shaw} type geometries. Under such confinement, a swimmer's hydrodynamic signature is that of a potential source dipole, and the long-range interactions among swimmers are obtained from the superposition of dipole singularities. Here, we recall the equations governing the positions and orientations of interacting asymmetric swimmers in doubly-periodic domains, and focus on the dynamics of swimmer pairs. We obtain two families of `relative equilibria'-type solutions that correspond to pursuit and synchronization of the two swimmers, respectively. Interestingly, the pursuit mode is stable for large tail swimmers whereas the synchronization mode is stable for large head swimmers. These results have profound implications on the collective behavior reported in several recent studies on populations of confined microswimmers.