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Resonant alignment of microswimmer trajectories in oscillatory shear flows

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Hope, A 
Croze, OA 
Poon, WCK 
Bees, MA 
Haw, MD 

Abstract

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.

Description

Keywords

shear flows, swimming

Journal Title

Physical Review Fluids

Conference Name

Journal ISSN

2469-990X
2469-990X

Volume Title

1

Publisher

American Physical Society
Sponsorship
Engineering and Physical Sciences Research Council (EP/J004847/1)
Engineering and Physical Sciences Research Council (EP/J007404/1)
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).