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DY: Fachverband Dynamik und Statistische Physik

DY 27: Fluid Physics 3 - organized by Stephan Weiss and Michael Wilczek (Göttingen)

DY 27.5: Talk

Tuesday, March 23, 2021, 15:30–15:50, DYa

Non-equilibrium phase transitions in bacterial vortex lattices — •Henning Reinken¹, Sebastian Heidenreich², Markus Bär², and Sabine H. L. Klapp¹ — ¹Technische Universität Berlin, Germany — ²Physikalisch-Technische Bundesanstalt, Berlin, Germany

Recent theoretical and experimental studies have shown that the turbulent vortex structures emerging in bacterial active fluids can be organized into regular vortex lattices by weak geometrical constraints such as small pillars [1,2].

Using a deterministic continuum-theoretical approach for the effective microswimmer velocity [3], we show that the emergence and disappearance of these non-equilibrium structures shares many similarities with second-order equilibrium phase transitions including critical behavior, e.g., long-range correlations and divergent susceptibility at the critical point. The exponents are very close to those of the 2D Ising model with nearest-neighbor interactions. A mapping to the Onsager solution allows us to identify an effective temperature linear in the strength of nonlinear advection.
[1] D. Nishiguchi, I. S. Aranson, A. Snezhko, and A. Sokolov,
[1] Nat. Commun. 9, 4486 (2018)
[2] H. Reinken, D. Nishiguchi, S. Heidenreich, A. Sokolov, M. Bär,
[2] S. H. L. Klapp, and I. S. Aranson, Commun. Phys. 3, 76 (2020)
[3] H. Reinken, S. H. L. Klapp, M. Bär, and S. Heidenreich,
[3] Phys. Rev. E 97, 022613 (2018)