Numerical studies of a granular gas in a host medium

The nonlinear dissipative Boltzmann equation for an granular gas diffusing in a elastically scattering host medium is investigated and numerically solved by means of direct stochastic simulation. The procedure requires an appropriate treatment of the two collision integrals involved, and of their different features. The algorithm is first tested versus exact results for macroscopic moments worked out in the Maxwellian-pseudo-molecules approximation, and then it is applied to the more realistic collision model of hard spheres for both elastic and inelastic encounters. When collisions with background are dominant, reliability of some hydrodynamic closures is then discussed by comparison of their outputs to the kinetic results achieved by the present DSMC approach.