Fluctuations of internal energy flow in a vibrated granular gas

A. Puglisi 1, P. Visco 1, 2, A. Barrat 1, E. Trizac 2, F. van Wijland 1, 3

Physical Review Letters 95 (2005) 110202

The non-equilibrium fluctuations of power flux in a fluidized granular media have been recently measured in an experiment [Phys. Rev. Lett. 92, 164301, 2004], which was announced to be a verification of the Fluctuation Relation (FR) by Gallavotti and Cohen. An effective temperature was also identified and proposed to be a useful probe for such non equilibrium systems. We explain these results in terms of a two temperature Poisson process. Within this model, supported by independent Molecular Dynamics simulations, power flux fluctuations do not satisfy the FR and the nature of the effective temperature is clarified. In the pursue of a hypothetical global quantity fulfilling the FR, this points to the need of considering other candidates than the power flux.

  • 1. Laboratoire de Physique Théorique d'Orsay (LPT),
    CNRS : UMR8627 – Université Paris XI - Paris Sud
  • 2. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
    CNRS : UMR8626 – Université Paris XI - Paris Sud
  • 3. Matière et Systèmes Complexes (MSC),
    CNRS : UMR7057 – Université Paris VII - Paris Diderot