title: Rotational propulsion enabled by inertia.
abstract: The fluid mechanics of small-scale locomotion has recently attracted considerable attention, due to its importance in cell motility and the design of artificial micro-swimmers for biomedical applications. Most studies on the topic consider the ideal limit of zero Reynolds number. In this paper, we investigate a simple propulsion mechanism --an up-down asymmetric dumbbell rotating about its axis of symmetry-- unable to propel in the absence of inertia in a Newtonian fluid. Inertial forces lead to continuous propulsion for all finite values of the Reynolds number. We study computationally its propulsive characteristics as well as analytically in the small-Reynolds-number limit. We also derive the optimal dumbbell geometry. The direction of propulsion enabled by inertia is opposite to that induced by viscoelasticity.
authors.affiliation: Commissariat à l'Energie Atomique, 33114, Le Barp, France, francois.nadal33@gmail.com.
authors.forename: François
authors.initials: F
authors.lastname: Nadal
authors.forename: On Shun
authors.initials: OS
authors.lastname: Pak
authors.forename: LaiLai
authors.initials: L
authors.lastname: Zhu
authors.forename: Luca
authors.initials: L
authors.lastname: Brandt
authors.forename: Eric
authors.initials: E
authors.lastname: Lauga
mesh_terms: D055592:Biophysical Phenomena; D002465:Cell Movement; D057446:Hydrodynamics; D008954:Models, Biological; D008962:Models, Theoretical; D009038:Motion; D012399:Rotation; D014783:Viscosity