Resonant alignment of microswimmer trajectories in oscillatory shear flows
Physical Review Fluids
American Physical Society
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Hope, A., Croze, O., Poon, W., Bees, M., & Haw, M. (2016). Resonant alignment of microswimmer trajectories in oscillatory shear flows. Physical Review Fluids, 1 (051201(R)) https://doi.org/10.1103/PhysRevFluids.1.051201
Oscillatory flows are commonly experienced by swimming micro-organisms in the environment, industrial applications, and rheological investigations. We characterize experimentally the response of the alga Dunaliella salina to oscillatory shear flows and report the surprising discovery that algal swimming trajectories orient perpendicular to the flow-shear plane. The ordering has the characteristics of a resonance in the driving parameter space. The behavior is qualitatively reproduced by a simple model and simulations accounting for helical swimming, suggesting a mechanism for ordering and criteria for the resonant amplitude and frequency. The implications of this work for active oscillatory rheology and industrial algal processing are discussed.
shear flows, swimming
O.A.C., W.C.K.P., M.D.H., and M.A.B. acknowledge support from the Carnegie Trust for the Universities of Scotland. O.A.C. further acknowledges support from the Winton Programme for the Physics of Sustainability and a Royal Society Research Grant; M.D.H. support from the Leverhulme Trust. O.A.C. and M.A.B. also acknowledge an EPSRC Mobility Grant (No. EP/J004847/1) and W.C.K.P. acknowledges the Programme Grant (No. EP/J007404/1) and ERC Advanced Grant (No. ERC-2013-AdG 340877-PHYSAPS).
Engineering and Physical Sciences Research Council (EP/J004847/1)
Engineering and Physical Sciences Research Council (EP/J007404/1)
External DOI: https://doi.org/10.1103/PhysRevFluids.1.051201
This record's URL: https://www.repository.cam.ac.uk/handle/1810/266379