Titcmt-94-* Power Law Velocity Uctuations Due to Inelastic Collisions in Numerically Simulated Vibrated Bed of Powder Typeset Using Revt E X

Distribution functions of relative velocities among particles in a vibrated bed of powder are studied both numerically and theoretically. In the solid phase where granular particles remain near their local stable states, the probability distribution is Gaussian. On the other hand, in the uidized phase, where the particles can exchange their positions, the distribution clearly deviates from Gaussian. This is interpreted with two analogies; aggregation processes and soft-to-hard turbulence transition in thermal convection. The non-Gaussian distribution is well-approximated by the t-distribution which is derived theoretically by considering the eeect of clustering by inelastic collisions in the former analogy.