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DY: Fachverband Dynamik und Statistische Physik
DY 16: Statistical Physics in Biological Systems (joint session DY/ BP)
DY 16.7: Talk
Wednesday, April 2, 2014, 11:15–11:30, ZEU 160
Self-propelled particles with alignment and anti-alignment — •Robert Großmann1, Pawel Romanczuk1, Markus Bär1, and Lutz Schimansky-Geier2 — 1Physikalisch-Technische Bundesanstalt, Berlin, Germany — 2Department of Physics, Humboldt-Universität zu Berlin, Germany
It was recently suggested that the observations of vortex structures in the local polarization of dense bacterial suspensions can be explained by a negative viscosity in the hydrodynamic equation for the polar order parameter [1]. Here, we propose a simple model of self-propelled particles interacting via a short-ranged alignment and a long-ranged anti-alignment, which may exhibit negative viscosity. This simple model allows us to systematically derive a coarse-grained description via a one-particle Fokker-Planck equation [2], and to analyze the relation of hydrodynamic transport coefficients on the microscopic parameters of the model. We explore the impact of different approximations required in the derivation of the coarse-grained theory on the validity of the linearized equations. Furthermore, we verify our results by comparing numerical simulations of the microscopic model with predictions of the coarse-grained theory.
[1] Dunkel, J. et al., New J. Phys., 15, 045016 (2013)
[2] Grossmann, R. et. al, New J. Phys., 15, 085014 (2013)