title: Microorganism billiards in closed plane curves.
abstract: Recent experiments have shown that many species of microorganisms leave a solid surface at a fixed angle determined by steric interactions and near-field hydrodynamics. This angle is completely independent of the incoming angle. For several collisions in a closed body this determines a unique type of billiard system, an aspecular billiard in which the outgoing angle is fixed for all collisions. We analyze such a system using numerical simulation of this billiard for varying tables and outgoing angles, and also utilize the theory of one-dimensional maps and wavefront dynamics. When applicable we cite results from and compare our system to similar billiard systems in the literature. We focus on examples from three broad classes: the ellipse, the Bunimovich billiards, and the Sinai billiards. The effect of a noisy outgoing angle is also discussed.
authors.affiliation: School of Engineering, Brown University, 02912, Providence, RI, USA. mkrieger@fas.harvard.edu.|Program for Evolutionary Dynamics, Harvard University, 02138, Cambridge, MA, USA. mkrieger@fas.harvard.edu.
authors.forename: Madison S
authors.initials: MS
authors.lastname: Krieger
mesh_terms: D002696:Chlamydomonas / Q000502:physiology; D004926:Escherichia coli / Q000502:physiology; D057446:Hydrodynamics; D008954:Models, Biological; D009068:Movement; D017711:Nonlinear Dynamics; D011387:Prokaryotic Cells / Q000502:physiology*
keywords: Flowing matter: Nonlinear Physics