Spinning swimming of Volvox by tangential helical wave

TL;DR

This paper models how Volvox uses tangential helical surface waves to achieve rotational swimming, analyzing two wave types and their efficiency based on Stokes flow equations.

Contribution

It introduces a detailed analysis of tangential helical waves on spherical surfaces, highlighting their role in Volvox's rotational swimming and comparing wave types.

Findings

Two types of tangential waves identified

Pressure disturbance increases rotation rate

Helical waves are relevant for Volvox's swimming

Abstract

The swimming of a sphere by means of tangential helical waves running along its surface is studied on the basis of the Stokes equations. Two types of tangential waves are found. The first of these is associated with a pressure disturbance and leads to a higher rate of net rotation than the second one for the same power. It is suggested that the helical waves are relevant for the rotational swimming of Volvox.