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Summary: Eur. Phys. J. B 42, 255261 (2004)
DOI: 10.1140/epjb/e2004-00377-4 THE EUROPEAN
PHYSICAL JOURNAL B
Energy and power fluctuations in vibrated granular gases
S. Auma^itre1
, J. Farago1
, S. Fauve1,a
, and S. Mc Namara2
1
Laboratorire de Physique Statistique, ´Ecole Normale Sup´erieure, UMR 8550, 24, rue Lhomond, 75005 Paris, France
2
ICA 1 Universit¨at Stuttgart, 70569 Stuttgart, Germany
Received 15 March 2004 / Received in final form 3 August 2004
Published online 14 December 2004 c EDP Sciences, Societ`a Italiana di Fisica, Springer-Verlag 2004
Abstract. Using two-dimensional numerical simulations of a granular gas excited by vibrating one of the
container boundaries, we study the fluctuations of its total kinetic energy, of the power injected into the
gas by the moving boundary and of the power dissipated by inelastic collisions. We show that an effective
number Nf of degrees of freedom that depends on the inelasticity of collisions can be extracted from the
probability density function (PDF) of the fluctuations of the total kinetic energy E. E /Nf is then an
intensive variable contrary to the usually defined granular temperature Tgr = E /N. We then show that
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