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Soft Matter and Biological Physics
Eur. Phys. J. E 11, 99-104 (2003)
DOI: 10.1140/epje/i2002-10149-2

Random inelasticity and velocity fluctuations in a driven granular gas

A. Barrat and E. Trizac

Laboratoire de Physique Théorique (UMR 8627 du CNRS), Bâtiment 210, Université de Paris-Sud, 91405 Orsay Cedex, France

Alain.Barrat@th.u-psud.fr

(Received 27 May 2002 and Received in final form 10 January 2003 / Published online: 27 May 2003)

Abstract
We analyze the deviations from Maxwell-Boltzmann statistics found in recent experiments studying velocity distributions in two-dimensional granular gases driven into a non-equilibrium stationary state by a strong vertical vibration. We show that in its simplest version, the "stochastic thermostat" model of heated inelastic hard spheres, contrary to what has been hitherto stated, is incompatible with the experimental data, although predicting a reminiscent high-velocity stretched-exponential behavior with an exponent 3/2. The experimental observations lead to refine a recently proposed random restitution coefficient model. Very good agreement is then found with experimental velocity distributions within this framework, which appears self-consistent and further provides relevant probes to investigate the universality of the velocity statistics.

PACS
45.70.-n - Granular systems.
05.20.Gg - Classical ensemble theory.
51.10.+y - Kinetic and transport theory of gases.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003