Propulsion of model monotrichous bacteria in weakly viscoelastic fluids
Alexander Morozov (University of Edinburgh)
Hydrodynamics of Swimming Microorganisms
Tue 9:00 - 10:30
Barus-Holley 191
Many bacteria employ flagella for propulsion through their environments. The classical "minimal model" of bacterial swimming, developed by Purcell [1] and Lighthill [2], considers an ellipsoidal body connected to a single rigid helical filament swimming in a Newtonian fluid and relates the propulsion velocity of the organism to the angular velocities of the flagellum and the body. Here we develop an analogous theory for bacterial propulsion through viscoelastic media. We calculate analytically the friction coefficients of a helix swimming in a weakly viscoelastic model fluid and relate the organism's kinematics to its propulsion speed. Our results are also relevant to the recent experiments on force-free swimming of helical filaments in polymer solutions [3] that showed non-monotonic dependence of the propulsion speed on the angular velocity of the helix. [1] E. M. Purcell, PNAS 9, 11307 (1997) [2] J. Lighthill, SIAM Rev. 18, 161 (1976) [3] B. Liu, T. R. Powers and K. S. Breuer, PNAS 108, 19516 (2011)