The dynamics of a self-phoretic Janus swimmer near a wall

TL;DR

This paper investigates how a planar wall influences the movement of self-phoretic Janus micro-swimmers, revealing that walls enhance propulsion via solute gradients but can cause re-orientation due to hydrodynamic effects.

Contribution

It classifies swimmer behaviors near walls based on their surface reactions and swimming direction, providing new insights into wall-induced propulsion and re-orientation mechanisms.

Findings

Wall-induced solute gradients promote propulsion along the wall.

Hydrodynamic effects lead to swimmer re-orientation away from the wall.

Behavior depends on whether the swimmer mainly absorbs or produces solutes.

Abstract

We study the effect of a nearby planar wall on the propulsion of a phoretic Janus micro-swimmer driven by asymmetric reactions on its surface which absorb reactants and generate products. We show that the behaviour of these swimmers near a wall can be classified ${\bf based \ on \ whether}$ the swimmers are ${\bf mainly}$ absorbing or producing reaction solutes ${\bf and \ whether}$ their swimming directions are such that the inert or active face is at the front. We find that the wall-induced solute gradients always promote swimmer propulsion along the wall while the effect of hydrodynamics leads to re-orientation of the swimming direction away from the wall.