Giacomo Gradenigo, CNR-ISC Roma #
Out-of-equilibrium correlations and entropy production in driven granular 
fluids: theory, simulations and experiments #
In a driven granular fluid energy is continuously gained from a thermal 
bath and lost through inelastic collisions.
The irreversible nature of this dynamics produces some correlations 
between the hydrodynamics fields, that are
absent at equilibrium. In this talk we summarize some results on the 
spectrum of velocity structure factors
in a driven granular fluid. This spectrum can be calculated analytically 
from a standard fluctuating hydrodynamic theory
and theoretical predictions are found in good agreement with the results 
of both event-driven molecular dynamic simulation
and real experiments, realized with a monolayer of inelastic beads 
fluidized with a vertical shaking.
We also derive a coarse-grained entropy production formula for granular 
fluid models,
making explicit the dependence of this observable from the 
out-of-equilibrium correlations between hydrodynamics fields
and showing that entropy production strongly depends on the kind of 
thermostat coupled to the granular fluid.