Active Particle Diffusion in Convection Roll Arrays

TL;DR

This study numerically explores how active Janus particles diffuse within convection roll arrays, revealing unique behaviors driven by self-propulsion, advection, and confinement, with implications for understanding active matter in fluid flows.

Contribution

It provides new insights into the diffusion regimes of active particles in convection flows, highlighting the effects of self-propulsion speed and confinement on their spatial distributions.

Findings

Active particles exhibit enhanced diffusion up to a critical speed.

Faster particles are guided along array edges, showing distinct diffusion regimes.

Active particles have inhomogeneous spatial distributions unlike passive ones.

Abstract

We numerically investigated the Brownian motion of active Janus particles in a linear array of planar counter-rotating convection rolls at high P\'eclet numbers. Similarly to passive particles, active microswimmers exhibit advection enhanced diffusion, but only for self-propulsion speeds up to a critical value. The diffusion of faster Janus particles is governed by advection along the array's edges, whereby distinct diffusion regimes are observed and characterized. Contrary to passive particles, the relevant spatial distributions of active Janus particles are inhomogeneous. These peculiar properties of active matter are related to the combined action of noise and self-propulsion in a confined geometry and hold regardless of the actual flow boundary conditions.