Regimes of motion of magnetocapillary swimmers

TL;DR

This paper investigates the motion regimes of a magnetocapillary swimmer using numerical simulations, revealing how frequency, surface tension, magnetic forces, and magnetic contributions influence its dynamics and reorientation behaviors.

Contribution

The study introduces a comprehensive numerical analysis of a magnetocapillary swimmer, identifying multiple motion regimes and effects of magnetic and surface tension parameters.

Findings

Maximum velocity at high frequencies near inverse coasting time

Propulsion regimes influenced by surface tension and magnetic force ratios

In-plane reorientations caused by constant magnetic contributions

Abstract

The dynamics of a triangular magnetocapillary swimmer is studied using the lattice Boltzmann method. Performing extensive numerical simulations taking into account the coupled dynamics of the fluid-fluid interface and of magnetic particles floating on it and driven by external magnetic fields we identify several regimes of the swimmer motion. In the regime of high frequencies the swimmer's maximum velocity is centered around the particle's inverse coasting time. Modifying the ratio of surface tension and magnetic forces allows to study the swimmer propagation in the regime of significantly lower frequencies mainly defined by the strength of the magnetocapillary potential. Finally, introducing a constant magnetic contribution in each of the particles in addition to their magnetic moment induced by external fields leads to another regime characterised by strong in-plane swimmer reorientations that resemble experimental observations.