Wetting dynamics by mixtures of fast and slow self-propelled particles

TL;DR

This paper investigates how mixtures of fast and slow self-propelled particles interact with surfaces, revealing complex wetting dynamics including overshoot behavior and two-stage composition evolution.

Contribution

It introduces a minimal model incorporating motility diversity to study active wetting, highlighting non-monotonic dynamics and transient particle fronts.

Findings

Wetting layer thickness exhibits an overshoot before reaching stationarity.

Particle composition evolves in two distinct stages.

Delayed avalanches and transient fronts cause non-monotonic behaviors.

Abstract

We study active surface wetting using a minimal model of bacteria that takes into account the intrinsic motility diversity of living matter. A mixture of "fast" and "slow" self-propelled Brownian particles is considered in the presence of a wall. The evolution of the wetting layer thickness shows an overshoot before stationarity and its composition evolves in two stages, equilibrating after a slow elimination of excess particles. Non-monotonic evolutions are shown to arise from delayed avalanches towards the dilute phase combined with the emergence of a transient particle front.