Power injected in a granular gas

A granular gas may be modeled as a set of hard-spheres undergoing inelastic collisions; its microscopic dynamics is thus strongly irreversible. As pointed out in several experimental works bearing on turbulent flows or granular materials, the power injected in a dissipative system to sustain a steady-state over an asymptotically large time window is a central observable. I will first present a phenomenological model able to describe the results of an experiment in which the steady state is achieved injecting energy trough the boundary (e.g. a vibrating wall). Then, I will describe an analytic approach allowing to determine the full distribution of the power injected in a model of randomly driven granular gas.