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BP: Fachverband Biologische Physik

BP 25: Statistical Physics in Biological Systems (joint DY/BP)

BP 25.7: Vortrag

Mittwoch, 2. April 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)