Swimmer-Types of Optimum Surface-Driven Active Particles

TL;DR

This paper investigates the optimal surface velocity profiles of microswimmers to minimize energy dissipation, revealing how geometry and deformation modes determine their pushers, pullers, or neutral types.

Contribution

It introduces a numerical method using a minimum dissipation theorem to classify optimal microswimmers based on their shape and deformation modes.

Findings

Symmetric swimmers tend to be neutral-type.

Asymmetric swimmers can be pushers, pullers, or neutral.

Stresslet strength depends nonlinearly on deformation modes.

Abstract

An optimal microswimmer with a given geometry has a surface velocity profile that minimizes energy dissipation for a given swimming speed. An axisymmetric swimmer can be puller-, pusher-, or neutral-type depending on the sign of the stresslet strength. We numerically investigate the type of optimal surface-driven active microswimmers using a minimum dissipation theorem for optimum microswimmers. We examine the hydrodynamic resistance and stresslet strength with nonlinear dependence on various deformation modes. The results show that microswimmers with fore-and-aft symmetry exhibit neutral-type behavior, while asymmetrical geometries exhibit pusher-, puller-type or neutral-type behavior, depending on the dominant deformation mode and the nonlinear dependence of the stresslet for an optimum microswimmer on deformation mode and amplitude.