DYNAMICS OF INELASTICALLY COLLIDING ROUGH SPHERES - RELAXATION OF TRANSLATIONAL AND ROTATIONAL ENERGY

We study the exchange of kinetic energy between translational and rota tional degrees of freedom for inelastic collisions of rough spheres. E ven if equipartition holds in the initial state it is immediately dest royed by collisions. The simplest generalization of the homogeneous co oling state allows for two temperatures, characterizing translational and rotational degrees of freedom separately. For times larger than a crossover frequency, which is determined by the Enskog frequency and t he initial temperature, both energies decay algebraically like t(-2) w ith a fixed ratio of amplitudes, different from 1.