A low-Reynolds-number treadmilling swimmer near a semi-infinite wall

TL;DR

This paper analyzes the movement of a microswimmer near a semi-infinite wall, revealing conditions under which it can escape, with implications for controlling microswimmers using probes or pipettes.

Contribution

It provides an analytical and numerical study of a treadmilling swimmer's trajectories near a wall, highlighting escape probabilities and potential control methods.

Findings

Many trajectories allow escape from the wall's vicinity.

Inserting a probe can push away microswimmers.

Analytical solutions for swimmer trajectories are derived.

Abstract

We investigate the behavior of a treadmilling microswimmer in a two-dimensional unbounded domain with a semi-infinite no-slip wall. The wall can also be regarded as a probe or pipette inserted into the flow. We solve the governing evolution equations in an analytical form and numerically calculate trajectories of the swimmer for several different initial positions and orientations. We then compute the probability that the treadmilling organism can escape the vicinity of the wall. We find that many trajectories in a 'wedge' around the wall are likely to escape. This suggests that inserting a probe or pipette in a suspension of organism may push away treadmilling swimmers.