Regensburg 2019 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 20: Active Matter B (joint session DY/CPP)
DY 20.5: Vortrag
Dienstag, 2. April 2019, 15:00–15:15, H3
Continuum model for active polar fluids with density variations — •Vasco M. Worlitzer1, Avraham Be'er2, Gil Ariel3, Markus Bär1, Holger Stark4, and Sebastian Heidenreich1 — 1Department of Mathematical Modelling and Data Analysis, Physikalisch-Technische Bundesanstalt, 10597 Berlin, Germany — 2Zuckerberg Institute for Water Research, The Jacob Blaustein Intitutes for Desert Research, Ben-Gurion University, Sede Boqer Campus, Midreshet Ben-Gurion, Israel — 3Department of Mathematics, Bar-Ilan University, Ramat Gan, Israel — 4Institute of Theoretical Physics, Technical University of Berlin, 10623 Berlin, Germany
Bacterial suspensions are intriguing examples for active polar fluids which exhibit large scale collective behavior from mesoscale turbulence to vortex lattices. For dense bacterial suspensions an effective fourth-order polar field theory was introduced modelling the collective dynamics in agreement with experimental findings [1,2]. However, in recent experiments of Bacillus subtilis suspensions anomalous velocity statistics and density variations are found which are not captured by the theory. In our contribution, we present a phenomenological theory for an active polar fluid with density and swimmer-velocity variations. We show that these variations result in an anomalous velocity statistics as observed in recent experiments [3].
[1] J Dunkel, S Heidenreich, K Drescher, HH Wensink, M Bär and RE Goldstein, Phys. Rev. Lett. 110 (2013) 228102. [2] S Heidenreich, J Dunkel, SHL Klapp and M Bär, Phys. Rev. E 94 (2016) 020601(R). [3] SD Ryan, G Ariel, A Be'er, Biophys J. (2016) 247.