A Simplest Swimmer at Low Reynolds Number: Three Linked Spheres

TL;DR

This paper introduces a minimalistic three-sphere swimmer model that achieves propulsion at low Reynolds number through non-reciprocal, periodic shape changes, offering insights into designing molecular-scale swimming devices.

Contribution

It presents the simplest possible low-Reynolds-number swimmer model with three linked spheres and demonstrates its ability to swim via non-reciprocal motion.

Findings

The three-sphere model can swim at low Reynolds number.

Periodic, non-reciprocal shape changes enable propulsion.

Potential application in molecular-size machine construction.

Abstract

We propose a very simple one-dimensional swimmer consisting of three spheres that are linked by rigid rods whose lengths can change between two values. With a periodic motion in a non-reciprocal fashion, which breaks the time-reversal symmetry as well as the translational symmetry, we show that the model device can swim at low Reynolds number. This model system could be used in constructing molecular-size machines.