SKM 2023 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 42: Poster: Active Matter, Soft Matter, Fluids

DY 42.9: Poster

Thursday, March 30, 2023, 13:00–16:00, P1

The Liquid-Glass-Jamming Rheology of Soft Active Particles — •Roland Wiese¹, Klaus Kroy¹, and Demian Levis^2,3 — ¹Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany — ²Departement de Fisica de la Materia Condensada, Facultat de Fisica, Universitat de Barcelona, Marti i Franquès 1, 08028 Barcelona, Spain — ³University of Barcelona Institute of Complex Systems (UBICS), Facultat de Fisica, Universitat de Barcelona, Marti i Franquès 1, 08028 Barcelona, Spain

We study the linear and nonlinear rheology of an active Brownian particle suspension at different densities. In the low density and low shear limits the flow is Newtonian. In this regime its linear response viscosity can be calculated via the Green-Kubo autocorrelation method and is found to scale with an effective temperature. In the nonlinear regime of high shearing rates shear thinning is observed universally for all parameters considered in our study. Above the critical density of the glass transition the dynamics becomes arrested, marked by the appearance of a finite yield stress. Increasing the self-propulsion of the active particles shifts the glass transition to higher densities by melting the amorphous solid. The yield stress enables us to construct a phase diagram in the spirit of jamming phase diagrams, but exchanging temperature with activity. For suffienctly high activities glassy physics becomes suppressed and the yield stress scales with a power law in the density, known from jammed granular materials.