Berlin 2024 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 33: Poster: Nonlinear Dynamics, Pattern Formation and Networks
DY 33.15: Poster
Mittwoch, 20. März 2024, 15:00–18:00, Poster C
The route to mesoscale turbulence in a model of active fluids — •Henning Reinken1,2, Sebastian Heidenreich3, Markus Bär3, and Sabine H. L. Klapp2 — 1Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany — 2Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany — 3Physikalisch-Technische Bundesanstalt Braunschweig und Berlin, Abbestr. 2-12, 10587 Berlin, Germany
Suspensions of microswimmers are a paradigmatic example of active fluids and are known to develop mesoscale turbulence, a state of dynamic vortex structures characterized by the presence of a characteristic length scale. Here, we employ a minimal model for the effective microswimmer velocity field [1,2] to explore how the turbulent state develops from regular, stationary vortex patterns when the strength of nonlinear advection is increased. To this end, we perform an extended stability analysis and uncover a linear instability, which follows from the mutual excitement and simultaneous growth of multiple perturbative modes. The extended analysis allows us to calculate a critical advection strength signifying the onset of mesoscale turbulence in the active fluid model, in very good agreement with numerical results. By this we establish an analogy to a critical Reynolds number in driven flow exhibiting inertial turbulence.
[1] Wensink, Dunkel, Heidenreich, Drescher, Goldstein, Löwen, Yeomans, Proc. Natl. Acad. Sci. U.S.A. 109, 14308 (2012)
[2] Reinken, Klapp, Bär, Heidenreich, Phys. Rev. E 97, 022613 (2018)
Keywords: Active Matter; Microswimmers; Mesoscale Turbulence; Pattern Formation; Hydrodynamic Instabilities