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DY: Fachverband Dynamik und Statistische Physik
DY 11: Active Fluids and Microswimmers (joint session DY/BP/CPP)
DY 11.4: Talk
Monday, March 18, 2024, 16:00–16:15, BH-N 243
Simultaneous emergence of active turbulence and odd viscosity in a colloidal chiral active system — •Joscha Mecke1,2, Yongxiang Gao1, Gerhard Gompper2, and Marisol Ripoll2 — 1Institute for Advanced Study, Shenzhen University, China — 2Institute of Biological Information Processing and Institute for Advanced Simulation, Forschungszentrum Jülich, Germany
Active fluids display collective phenomena such as active turbulence or odd viscosity, which refer to spontaneous complex and transverse flow. We report the simultaneous emergence of these seemingly separate phenomena in experiment for a chiral active fluid composed of a carpet of standing and spinning colloidal rods, and in simulations for synchronously rotating hard discs in a hydrodynamic explicit solvent (see also Commun. Phys. 6, 324 (2023), https://doi.org/10.1038/s42005-023-01442-3). Stresses among the colloids encompass rotational and odd shear contributions absent in usual fluids. Rotational viscosity couples the colloids' rotation to translation, causing active turbulence. Odd viscosity involves a perpendicular coupling of shear stresses, leading to an effective pressure pointing into or out of the emergent vortices. We quantify the two phenomena in experiments and simulation using the same setup. Both rotational and odd viscosity originate from the same source and the system behaviour hinges on the propagation of odd stresses via long-ranged hydrodynamics. Our findings are relevant for the understanding of biological systems and for the design of microrobots with collective self-organised behaviour.
Keywords: Chiral active fluids; Simulation; Experiment; Odd viscosity; Active turbulence