Some studies on granular gases under chaotic stirring

We study the spatial structure of a granular material,
$N$ particles subject to inelastic mutual collisions, when it is
stirred by a bidimensional smooth chaotic flow. A simple dynamical
model is introduced where four different time scales are explicitly
considered: i) the Stokes time, accounting for the inertia of the
particles, ii) the mean collision time among the grains, iii) the
typical time scale of the flow, and iv) the inverse of the Lyapunov
exponent of the chaotic flow. We also introduce some
preliminar studies about a continuum description of the system.