Enhanced clamshell swimming with asymmetric beating at low Reynolds number

TL;DR

This paper investigates how asymmetric beating patterns in a multi-filament clamshell swimmer at low Reynolds number can enhance propulsion, exploring elastic and segmental models with hydrodynamic interactions.

Contribution

It introduces a simple boundary-driven multi-filament swimmer model and demonstrates how asymmetric beating improves swimming performance.

Findings

Optimal included angles and elastoviscous numbers identified

Segmental models replicate elastic clamshell dynamics

Asymmetric beating significantly enhances propulsion

Abstract

A single flexible filament can be actuated to escape from the scallop theorem and generate net propulsion at low Reynolds number. In this work, we study the dynamics of a simple boundary-driven multi-filament swimmer, a two-arm clamshell actuated at the hinged point, using a nonlocal slender body approximation with full hydrodynamic interactions. We first consider an elastic clamshell consisted of flexible filaments with intrinsic curvature, and then build segmental models consisted of rigid segments connected by different mechanical joints with different forms of response torques. The simplicity of the system allows us to fully explore the effect of various parameters on the swimming performance. Optimal included angles and elastoviscous numbers are identified. The segmental models capture the characteristic dynamics of the elastic clamshell. We further demonstrate how the swimming performance can be significantly enhanced by the asymmetric beating patterns induced by biased torques.