Emergent rheotaxis of shapechanging swimmers in Poiseuille flow
Abstract
A simple model for the motion of shapechanging swimmers in Poiseuille flow was recently proposed and numerically explored by Omori et al. (J. Fluid Mech., vol. 930, 2022, A30). These explorations hinted that a small number of interacting mechanics can drive longtime behaviours in this model, cast in the context of the wellstudied alga Chlamydomonas and its rheotactic behaviours in such flows. Here, we explore this model analytically via a multiplescale asymptotic analysis, seeking to formally identify the causal factors that shape the behaviour of these swimmers in Poiseuille flow. By capturing the evolution of a Hamiltonianlike quantity, we reveal the origins of the longterm drift in a single swimmerdependent constant, whose sign determines the eventual behaviour of the swimmer. This constant captures the nonlinear interaction between the oscillatory speed and effective hydrodynamic shape of deforming swimmers, driving drift either towards or away from rheotaxis.
 Publication:

Journal of Fluid Mechanics
 Pub Date:
 August 2022
 DOI:
 10.1017/jfm.2022.474
 arXiv:
 arXiv:2203.12516
 Bibcode:
 2022JFM...944R...2W
 Keywords:

 Physics  Fluid Dynamics;
 Mathematics  Dynamical Systems;
 Physics  Biological Physics
 EPrint:
 10 pages, 4 figures