Published in Physics of Fluids, Volume 24, Issue 081703, January 1, 2012, pages 1-7.
At the time of publication, author Nathan Keim was not yet affiliated with Cal Poly
The definitive version is available at https://doi.org/10.1063/1.4746792.
Conventionally, a microscopic particle that performs a reciprocal stroke cannot move through its environment. This is because at small scales, the response of simple Newtonian fluids is purely viscous and flows are time-reversible. We show that by contrast, fluid elasticity enables propulsion by reciprocal forcing that is otherwise impossible. We present experiments on rigid objects actuated reciprocally in viscous fluids, demonstrating for the first time a purely elastic propulsion set by the object’s shape and boundary conditions. We describe two different artificial “swimmers” that experimentally realize this principle.
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