Berlin 2012 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 29: Posters II
DY 29.49: Poster
Donnerstag, 29. März 2012, 17:00–19:00, Poster A
Transport Coefficients and Speed of Sound of a Granular Fluid from Static Correlation Functions — •Till Kranz1,2 and Annette Zippelius1,2 — 1MPI für Dynamik & Selbstorganisation, Göttingen — 2Institut für Theoretische Physik, Uni Göttingen
In order to reach a stationary state, granular, i.e., dissipative systems need an external driving. One of the many possible methods is to fluidize the system by a random force. It has been shown that the behavior of such a granular fluid on large length scales is well described by fluctuating hydrodynamics [1]. We exploit this description to extract material properties form event driven simulations.
For equilibrium fluids, the speed of sound, c, is directly related to the long wave length limit of the static structure factor, S(q), via a fluctuation dissipation relation, c2 = kBT/mS(q→0). We show that a generalized version of this relation also holds for the driven granular fluid. Using this relation, we measure the speed of sound of a granular fluid and find results that agree well with dynamic measurements [2] and with theoretical predictions.
The fluctuations dissipation theorem for equilibrium fluids makes it impossible to extract transport coefficients from static measurements. We show that, in contrast, it is possible to measure the viscosity of a granular fluid from the static current correlator.
[1] T. P. C. van Noije et al., PRE 59, 4326 (1999)
[2] K. Vollmayr-Lee et al., PRE 83, 011301 (2011)