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Swimming in an anisotropic fluid: How speed depends on alignment angle
Phys. Rev. Fluids 2, 123102 – Published 27 December, 2017
DOI: https://doi.org/10.1103/PhysRevFluids.2.123102
Abstract
Orientational order in a fluid affects the swimming behavior of flagellated microorganisms. For example, bacteria tend to swim along the director in lyotropic nematic liquid crystals. To better understand how anisotropy affects propulsion, we study the problem of a sheet supporting small-amplitude traveling waves, also known as the Taylor swimmer, in a nematic liquid crystal. For the case of weak anchoring of the nematic director at the swimmer surface and in the limit of a minimally anisotropic model, we calculate the swimming speed as a function of the angle between the swimmer and the nematic director. The effect of the anisotropy can be to increase or decrease the swimming speed, depending on the angle of alignment. We also show that elastic torque dominates the viscous torque for small-amplitude waves and that the torque tends to align the swimmer along the local director.
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