A. Puglisi 1, A. Sarracino 2, G. Gradenigo 3, D. Villamaina 4
Granular Matter 14 (2012) 235-238
A massive intruder in a homogeneously driven granular fluid, in dilute configurations, performs a memory-less Brownian motion with drag and temperature simply related to the average density and temperature of the fluid. At volume fraction $\sim 10-50%$ the intruder’s velocity correlates with the local fluid velocity field: such situation is approximately described by a system of coupled linear Langevin equations equivalent to a generalized Brownian motion with memory. Here one may verify the breakdown of the Fluctuation-Dissipation relation and the presence of a net entropy flux – from the fluid to the intruder – whose fluctuations satisfy the Fluctuation Relation.
- 1. Dipartimento di Fisica,
Università La Sapienza - 2. Dipartimento di Fisica,
CNR – Consiglio Nationale delle Ricerche - 3. Dipartimento di Fisica,
CNR – Consiglio Nationale delle Ricerche - 4. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
CNRS : UMR8626 – Université Paris XI – Paris Sud