Regensburg 2022 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 46: Poster Session: Complex Fluids, Soft Matter, Active Matter, Glasses and Granular Materials

DY 46.7: Poster

Thursday, September 8, 2022, 15:00–18:00, P2

Ising-like critical behavior of vortex lattices in an active fluid — •Henning Reinken¹, Sebastian Heidenreich², Markus Bär², and Sabine H. L. Klapp¹ — ¹Technische Universität Berlin — ²Physikalisch-Technische Bundesanstalt Berlin

Turbulent vortex structures emerging in bacterial active fluids can be organized into regular vortex lattices by weak geometrical constraints such as obstacles [1,2]. Here we show, using a continuum-theoretical approach [3], that the formation and destruction of these patterns exhibit features of a continuous second-order equilibrium phase transition, including long-range correlations, divergent susceptibility, and critical slowing down. The emerging vorticity field can be mapped onto a two-dimensional (2D) Ising model with antiferromagnetic nearest-neighbor interactions by coarse-graining. The resulting effective temperature is found to be proportional to the strength of the nonlinear advection in the continuum model [4].
[1] D. Nishiguchi, I. S. Aranson, A. Snezhko, and A. Sokolov, Nat. Commun. 9, 4486 (2018)
[2] H. Reinken, D. Nishiguchi, S. Heidenreich, A. Sokolov, M. Bär, 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, Phys. Rev. E 97, 022613 (2018)
[4] H. Reinken, S. Heidenreich, M. Bär, and S. H. L. Klapp, Phys. Rev. Lett. 128, 048004 (2022)