Regensburg 2022 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 11: Granular Matter and Contact Dynamics

DY 11.2: Vortrag

Montag, 5. September 2022, 15:45–16:00, H19

Rare Fluctuations in Sheared 2D LJ Fluids — •Daniel Dernbach and Jürgen Vollmer — Institut für Theoretische Physik, Universität Leipzig, Brüderstr. 16, D-04103 Leipzig, Germany

A distinguishing feature of sheared particulate flows are very large fluctuations in the dissipation, i.e. the product of the local velocity gradient and the local shear stress. At times, it even takes negative values (rare fluctuations). Surprisingly, the probability of rare fluctuations vanishes close to jamming [1], a far-from-equilibrium critical point where fluctuations are expected to be large.

Here, we compare this setting to the motion of classical fluids with attractive, elastic interactions. Specifically, we consider the transition from fluid to plastic flow in a two-dimensional (2D) Lennard-Jones (LJ) fluid subjected to a Nosé-Hoover thermostat.

Close to its critical rigidity transition this time-reversible sheared dynamics also features a drop of the probability of rare fluctuations. We will scrutinize the analogies and differences between the emergence of rare fluctuations in irreversible particulate flow and in time-reversible classical dynamics.
[1] Rahbari, Saberi, Park, Vollmer, Nat. Commun. 8, 11 (2017)