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DY: Fachverband Dynamik und Statistische Physik

DY 12: Posters DY - Fluid Physics, Active Matter, Complex Fluids, Soft Matter and Glasses (joint session DY/BP)

DY 12.22: Poster

Monday, March 22, 2021, 14:00–16:30, DYp

Fluctuations of a driven tracer in a viscoelastic bath — •Juliana Caspers and Matthias Krüger — Institut für Theoretische Physik, Göttingen

Recently, viscoelastic fluids have attracted attention as their large structural relaxation times induce a variety of new phenomena such as nontrivial back reactions of the bath on a driven probe particle. Berner et al [1] found particle oscillations in the linear response regime, both in theory and experiment. Moreover, Müller et al [2] investigated effects of nonlinear baths in equilibrium. They observed inter-dependencies entering the coefficients in an effective linear generalized Langevin equation. For example, the friction memory kernel depends on properties of the external trap [3] or on the bare tracer friction in the case of an overdamped setting. In [1,2], the simple model of a confined tracer particle interacting via a stochastic Prandtl-Tomlinson model with a bath particle was found to be a good candidate to mimick the properties of a nonlinear viscoelastic bath. This work focuses on the interplay of the external trap that confines the tracer particle and the nonlinearity of the bath. In a nonequilibrium situation we made a first observation of shear thickening, an increase in the microrheological friciton coefficient for a certain regime of driving velocities.
[1] J. Berner, B. Müller, J. R. Gomez-Solano, M. Krüger, and C. Bechinger. Nat. Commun., 9(1):999, 2018

[2] B. Müller, J. Berner, C. Bechinger, and M. Krüger. New J. Phys., 22:023014, 2020

[3] J. O. Daldrop, B. G. Kowalik, and R. R. Netz. Phys. Rev. X, 7:041065, 2017