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DY: Fachverband Dynamik und Statistische Physik

DY 18: Granular matter / contact dynamics

DY 18.6: Vortrag

Mittwoch, 25. März 2009, 17:45–18:00, HÜL 386

The Velocity Autocorrelation Function of a Driven Granular Fluid — •W. Till Kranz, Andrea Fiege, and Annette Zippelius — Institute for Theoretical Physics, University of Göttingen and MPI for Dynamic and Self Organization, Göttingen, Germany

We extend the equilibrium mode coupling theory (MCT) of molecular fluids [1] to the steady state of a driven granular fluid. This allows us to derive an analytic expression for the velocity autocorrelation function ψ(t) ∼ ⟨v_s(0)v_s(t)⟩. We will briefly outline the key assumptions that form the basis of our derivation. Subsequently we will discuss how the rich phenomenology already present in the equilibrium hard sphere gas [2] carries over to the non-equilibrium case of a granular fluid. In particular we will focus on long-time tails, backscattering and the suppression of diffusion at high densities. In order to asses the range of validity of the theoretical predictions we compare it to extensive numerical data that has recently become available [3].

[1] W. Götze, in Liquids, Freezing and Glass Transition (North Holland, 1991)

[2] B. J. Alder, E. Wainwright, Phys. Rev. Lett. 18, 988 (1967)

[3] A. Fiege, T. Aspelmeier, A. Zippelius, arXiv:0809.4432 to appear in PRL