title: Twirling and whirling: viscous dynamics of rotating elastic filaments.
abstract: Motivated by diverse phenomena in cellular biophysics, including bacterial flagellar motion and DNA transcription and replication, we study the overdamped nonlinear dynamics of a rotationally forced filament with twist and bend elasticity. Competition between twist injection, twist diffusion, and writhing instabilities is described by coupled PDEs for twist and bend evolution. Analytical and numerical methods elucidate the twist/bend coupling and reveal two regimes separated by a Hopf bifurcation: (i) diffusion-dominated axial rotation, or twirling, and (ii) steady-state crankshafting motion, or whirling. The consequences of these phenomena for self-propulsion are investigated, and experimental tests proposed.
authors.affiliation: Department of Physics, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Wolgemuth
authors.forename: T R
authors.initials: TR
authors.lastname: Powers
authors.forename: R E
authors.initials: RE
authors.lastname: Goldstein
mesh_terms: D018407:Bacterial Physiological Phenomena; D004247:DNA / Q000737:chemistry / Q000648:ultrastructure; D004058:Diffusion; D004548:Elasticity; D005407:Flagella / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D008124:Locomotion / Q000502:physiology; D012399:Rotation; D014783:Viscosity
chemical_list: D004247:DNA