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Microswimmer Propulsion by Two Steadily Rotating Helical Flagella

Department of Applied Mathematics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
Micromachines 2019, 10(1), 65;
Received: 31 December 2018 / Revised: 15 January 2019 / Accepted: 15 January 2019 / Published: 18 January 2019
(This article belongs to the Special Issue Microswimmer)
PDF [1328 KB, uploaded 18 January 2019]


Many theoretical studies of bacterial locomotion adopt a simple model for the organism consisting of a spheroidal cell body and a single corkscrew-shaped flagellum that rotates to propel the body forward. Motivated by experimental observations of a group of magnetotactic bacterial strains, we extended the model by considering two flagella attached to the cell body and rotating about their respective axes. Using numerical simulations, we analyzed the motion of such a microswimmer in bulk fluid and close to a solid surface. We show that positioning the two flagella far apart on the cell body reduces the rate of rotation of the body and increases the swimming speed. Near surfaces, we found that swimmers with two flagella can swim in relatively straight trajectories or circular orbits in either direction. It is also possible for the swimmer to escape from surfaces, unlike a model swimmer of similar shape but with only a single flagellum. Thus, we conclude that there are important implications of swimming with two flagella or flagellar bundles rather than one. These considerations are relevant not only for understanding differences in bacterial morphology but also for designing microrobotic swimmers. View Full-Text
Keywords: bacterial locomotion; microswimmer; wall effect; multiple flagella; magnetotactic bacteria; boundary element method bacterial locomotion; microswimmer; wall effect; multiple flagella; magnetotactic bacteria; boundary element method

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Shum, H. Microswimmer Propulsion by Two Steadily Rotating Helical Flagella. Micromachines 2019, 10, 65.

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