The Hatano-Sasa equality: Transitions between steady states in a granular gas
Laboratoire de Physique de l'École Normale Supérieure de Lyon, Université de Lyon, CNRS UMR 5672 46 Allée d'Italie, 69364 Lyon cedex 7, France, EU
Received: 15 August 2012
Accepted: 11 October 2012
An experimental study is presented, about transitions between Non-Equilibrium Steady States (NESS) in a dissipative medium. The core device is a small rotating blade that imposes cycles of increasing and decreasing forcings to a granular gas, shaken independently. The velocity of this blade is measured, subject to the transitions imposed by the periodic torque variation. The Hatano-Sasa (HS) equality, that generalises the second principle of thermodynamics to NESS, is verified with a high accuracy (a few 10−3), at different variation rates. Besides, it is observed that the fluctuating velocity at fixed forcing follows a generalised Gumbel distribution. A rough evaluation of the mean free path in the granular gas suggests that it might be a correlated system, at least partially.
PACS: 05.70.Ln – Nonequilibrium and irreversible thermodynamics / 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion / 47.70.Nd – Nonequilibrium gas dynamics
© EPLA, 2012