Elastohydrodynamics of swimming helices: effects of flexibility and confinement
Abstract
Motivated by bacterial transport through porous media, here we study the swimming of an actuated, flexible helical filament in both three-dimensional free space and within a cylindrical tube whose diameter is much smaller than the length of the helix. The filament, at rest, has a native helical shape modeled after the geometry of a typical bacterial flagellar bundle. The finite length filament is a free swimmer, and is driven by an applied torque as well as a counter-torque (of equal strength and opposite direction) that represents a virtual cell body. We use a regularized Stokeslet framework to examine the shape changes of the flexible filament in response to the actuation as well as the swimming performance as a function of the nondimensional Sperm number that characterizes the elastohydrodynamic system. We also show that a modified Sperm number may be defined to characterize the swimming progression within a tube. Finally, we demonstrate that a helical filament whose axis is not aligned with the tube axis can exhibit centering behavior in the narrowest tubes.
Keywords
Cite
@article{arxiv.1811.06959,
title = {Elastohydrodynamics of swimming helices: effects of flexibility and confinement},
author = {John LaGrone and Ricardo Cortez and Lisa Fauci},
journal= {arXiv preprint arXiv:1811.06959},
year = {2019}
}