An elastic two-sphere swimmer in Stokes flow

TL;DR

This paper demonstrates that an elastic two-sphere swimmer can achieve propulsion in Stokes flow through non-reciprocal deformations caused by elasticity, highlighting potential for designing artificial microswimmers.

Contribution

It introduces a model of a two-sphere swimmer with elastic deformation capable of propulsion despite reversible actuation, revealing elasticity's role in low Reynolds number swimming.

Findings

Elastic deformations enable propulsion despite reciprocal actuation.

Weak elastic effects significantly influence microswimmer locomotion.

The model suggests new design principles for artificial microswimmers.

Abstract

Swimming at low Reynolds number in Newtonian fluids is only possible through non-reciprocal body deformations due to the kinematic reversibility of the Stokes equations. We consider here a model swimmer consisting of two linked spheres, wherein one sphere is rigid and the other an incompressible neo-Hookean solid. The two spheres are connected by a rod which changes its length periodically. We show that the deformations of the body are non-reciprocal despite the reversible actuation and hence, the elastic two-sphere swimmer propels forward. Our results indicate that even weak elastic deformations of a body can affect locomotion and may be exploited in designing artificial microswimmers.