ENERGY NONEQUIPARTITION IN SYSTEMS OF INELASTIC, ROUGH SPHERES

We calculate and verify with simulations the ratio between the average translational and rotational energies of systems with rough, inelasti c particles, either forced or freely cooling. The ratio shows a nonequ ipartition of energy. In stationary flows, this ratio depends mainly o n the particle roughness, but in nonstationary flows, such as freely c ooling granular media, it also depends strongly on the normal dissipat ion. The approach presented here unifies and simplifies different resu lts obtained by more elaborate kinetic theories. We observe that the b oundary induced energy flux plays an important role.