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DY: Fachverband Dynamik und Statistische Physik
DY 42: Fluid Physics of Life (joint session DY/BP)
DY 42.5: Vortrag
Mittwoch, 18. März 2020, 16:15–16:30, ZEU 160
Boundary conditions for polar active fluids exhibiting mesoscale turbulence — •Sebastian Heidenreich1, Henning Reinken2, Daiki Nishiguchi3, Andrey Sokolov4, Igor S. Aranson5, Sabine H. L. Klapp2, and Markus Bär1 — 1Physikalisch Technische Bundesanstalt Braunschweig und Berlin — 2Technische Universität Berlin — 3University of Tokyo, Japan — 4Argonne National Laboratory, USA — 5Pennsylivania State University, USA
Bacterial suspensions are intriguing examples for active polar fluids which exhibit large-scale collective behaviour from mesoscale turbulence to vortex lattices. The bulk collective motion is well described by a continuum equation with derivatives up to the fourth order [1]. That simple model reproduces experimental findings of mesoscale turbulence and was recently derived from a minimal micro-swimmer model. However, the treatment of boundaries to describe the collective motion in a confinement or near walls remains so far unknown. In the talk, we propose boundary conditions for active polar fluids suitable to describe recent experiments of Bacillus subtilis bacteria moving in an array of lithographic designed pillars [2]. Furthermore, we describe the collective motion of bacteria around single pillars of different sizes in experiments and show that the model with the mentioned boundary conditions reproduces this behavior faithfully.
[1] J. Dunkel, S. Heidenreich, M. Bär and R. E. Goldstein, New. J. Phys. 15, 040516 (2013). [2] D. Nishiguchi, I. S. Aranson, A. Snezhko and A. Sokolov Nat. Comm. 9, 4486 (2018).