Abstract
We combine experiments with simulations to investigate the fluid-structure interaction of a flexible helical rod rotating in a viscous fluid, under low Reynolds number conditions. Our analysis takes into account the coupling between the geometrically nonlinear behavior of the elastic rod with a nonlocal hydrodynamic model for the fluid loading. We quantify the resulting propulsive force, as well as the buckling instability of the originally helical filament that occurs above a critical rotation velocity. A scaling analysis is performed to rationalize the onset of this instability. A universal phase diagram is constructed to map out the region of successful propulsion and the corresponding boundary of stability is established. Comparing our results with data for flagellated bacteria suggests that this instability may be exploited in nature for physiological purposes.
- Received 13 June 2015
DOI:https://doi.org/10.1103/PhysRevLett.115.168101
© 2015 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Buckling in Bacteria Tails
Published 13 October 2015
Experiments with rotating elastic rods mimic the behavior of swimming bacteria, showing how their tails buckle above a certain rotation speed.
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