The effect of gait on swimming in viscoelastic fluids

TL;DR

This paper derives formulas for swimming speeds of simplified bodies in viscoelastic fluids, revealing how gait and deformation modes influence propulsion compared to Newtonian fluids.

Contribution

It introduces formulas for swimming in complex fluids and analyzes how deformation modes affect swimming speed in viscoelastic environments.

Findings

Multiple deformation modes can increase swimming speed in viscoelastic fluids.

Speed changes are directly linked to variations in thrust.

Small-amplitude deformations influence swimming efficiency in complex fluids.

Abstract

In this paper, we give formulas for the swimming of simplified two-dimensional bodies in complex fluids using the reciprocal theorem. By way of these formulas we calculate the swimming velocity due to small-amplitude deformations on the simplest of these bodies, a two-dimensional sheet, to explore general conditions on the swimming gait under which the sheet may move faster, or slower, in a viscoelastic fluid compared to a Newtonian fluid. We show that in general, for small amplitude deformations, a speed increase can only be realized by multiple deformation modes in contrast to slip flows. Additionally, we show that a change in swimming speed is directly due to a change in thrust generated by the swimmer.