Dynamics of artificial bacterial flagella

ORAL

Abstract

Artificial bacterial flagella (ABF) are small-scale rigid helices actuated by an external rotating magnetic field and therefore able to propel in a viscous fluid. In experiments, ABF are observed to display wobbling motion at low frequencies and a transition to directed swimming at higher frequencies. We use here a combination of numerics and asymptotics to provide a theoretical explanation for this dynamics. In particular we show that the wobbling angle - the angle between the direction of propulsion and the axis of the helix - is inversely proportional to the Mason number, a dimensionless number given by the ratio of the magnitudes of viscous torque to magnetic torque. Our theoretical predictions agree well with experimental results.

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Authors

  • Yi Man

    Department of Mechanical and Aerospace Engineering, University of California, San Diego

  • Eric Lauga

    Department of Mechanical and Aerospace Engineering, University of California, San Diego, Department of Mechanical and Aerospace Engineering, University of California San Diego, Department of Mechanical and Aerospace Engineering, UC San Diego, University of California San Diego, University of California at San Diego, University of California, San Diego