The swimming of a deforming helix

Koens, Lyndon; Zhang, Hang; Moeller, Martin; Mourran, Ahmed; Lauga, Eric

Abstract

Abstract.: Many microorganisms and artificial microswimmers use helical appendages in order to generate locomotion. Though often rotated so as to produce thrust, some species of bacteria such Spiroplasma, Rhodobacter sphaeroides and Spirochetes induce movement by deforming a helical-shaped body. Recently, artificial devices have been created which also generate motion by deforming their helical body in a non-reciprocal way (A. Mourran et al. Adv. Mater. 29, 1604825, 2017). Inspired by these systems, we investigate the transport of a deforming helix within a viscous fluid. Specifically, we consider a swimmer that maintains a helical centreline and a single handedness while changing its helix radius, pitch and wavelength uniformly across the body. We first discuss how a deforming helix can create a non-reciprocal translational and rotational swimming stroke and identify its principle direction of motion. We then determine the leading-order physics for helices with small helix radius before considering the general behaviour for different configuration parameters and how these swimmers can be optimised. Finally, we explore how the presence of walls, gravity, and defects in the centreline allow the helical device to break symmetries, increase its speed, and generate transport in directions not available to helices in bulk fluids. Graphical abstract: [Figure not available: see fulltext.].

Citation

Koens, L., Zhang, H., Moeller, M., Mourran, A., & Lauga, E. (2018). The swimming of a deforming helix. European Physical Journal E, 41(10), Article 119. https://doi.org/10.1140/epje/i2018-11728-2

• Journal Article Type: Article
• Acceptance Date: Sep 7, 2018
• Online Publication Date: Oct 11, 2018
• Publication Date: 2018
• Deposit Date: Jan 25, 2022
• Publicly Available Date: Feb 8, 2022
• Journal: European Physical Journal E
• Print ISSN: 1292-8941
• Electronic ISSN: 1292-895X
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 41
• Issue: 10
• Article Number: 119
• DOI: https://doi.org/10.1140/epje/i2018-11728-2
• Public URL: https://hull-repository.worktribe.com/output/3916602