Modeling microscopic swimmers at low Reynolds number

TL;DR

This paper compares numerical methods for modeling low Reynolds number swimmers, introduces a new class of flexible micro-swimmers, and analyzes their efficiency and motion through simulations and theoretical models.

Contribution

It presents a comparative study of numerical approaches and proposes a novel design for three-dimensional micro-swimmers with flexible structures.

Findings

Different numerical methods show consistent results for known models

Generalized three-bead swimmers can efficiently move in three dimensions

Elastic filaments exhibit swimming behaviors similar to experimental devices

Abstract

We employ three numerical methods to explore the motion of low Reynolds number swimmers, modeling the hydrodynamic interactions by means of the Oseen tensor approximation, lattice Boltzmann simulations and multiparticle collision dynamics. By applying the methods to a three bead linear swimmer, for which exact results are known, we are able to compare and assess the effectiveness of the different approaches. We then propose a new class of low Reynolds number swimmers, generalized three bead swimmers that can change both the length of their arms and the angle between them. Hence we suggest a design for a microstructure capable of moving in three dimensions. We discuss multiple bead, linear microstructures and show that they are highly efficient swimmers. We then turn to consider the swimming motion of elastic filaments. Using multiparticle collision dynamics we show that a driven filament behaves in a qualitatively similar way to the micron-scale swimming device recently demonstrated by Dreyfus et al.