Motion-reversal in a simple microscopic swimmer

TL;DR

This paper investigates a microscopic swimmer driven by a rotating magnetic field, revealing a frequency-dependent reversal of motion direction through simulations and scaling analysis.

Contribution

It introduces a simple model of a magnetic swimmer showing motion reversal at a critical frequency, combining hydrodynamic simulations with scaling arguments.

Findings

Swimmer moves forward below a critical frequency

Motion reverses above the critical frequency

Hydrodynamic simulations confirm the reversal phenomenon

Abstract

We study the motion of a microscopic swimmer composed of a semiflexible polymer anchored at the surface of a magnetic sphere using hydrodynamic simulations and scaling arguments. The swimmer is driven by a rotating magnetic field, and displays forward and backward motion depending on the value of the rotational frequency. In particular, the system exhibits forward thrust for frequencies below a critical frequency $\omega^*$, while above $\omega^*$ the motion is reversed.