Detention times of microswimmers close to surfaces: Influence of hydrodynamic interactions and noise

TL;DR

This paper develops a framework to analyze how hydrodynamic interactions and noise affect the detention times of microswimmers near surfaces, with implications for biofilm formation.

Contribution

It introduces a general method to calculate detention time distributions considering hydrodynamics and noise, comparing different swimmer models including the squirmer.

Findings

Pullers have significantly longer detention times than source dipoles.

Hydrodynamic interactions can increase or decrease detention times depending on swimmer type.

Validation with multi-particle collision dynamics confirms the theoretical predictions.

Abstract

After colliding with a surface, microswimmers reside there during the detention time. They accumulate and may form complex structures such as biofilms. We introduce a general framework to calculate the distribution of detention times using the method of first-passage times and study how rotational noise and hydrodynamic interactions influence the escape from a surface. We compare generic swimmer models to the simple active Brownian particle. While the respective detention times of source dipoles are smaller, the ones of pullers are larger by up to several orders of magnitude, and pushers show both trends. We apply our results to the more realistic squirmer model, for which we use lubrication theory, and validate them by simulations with multi-particle collision dynamics.