Transport of a heated granular gas in a washboard potential
  We study numerically the motion of a one dimensional array of Brownian particles in a washboard potential, driven by an external stochastic force and interacting via short range repulsive forces. In particular, we investigate the role of instantaneous elastic and inelastic collisions on the system dynamics and transport. The system displays a locked regime, where particles may move only via activated processes and a running regime where particles drift along the direction of the applied field. By tuning the value of the friction parameter controlling the Brownian motion we explore both the overdamped dynamics and the underdamped dynamics. In the two regimes we considered the mobility and the diffusivity of the system as functions of the tilt and other relevant control parameters such as, coefficient of restitution, particle size and total number of particles. We find that, while in the overdamped regime, the results for the interacting systems present similarities with the known non-interacting case, in the underdamped regime, the inelastic collisions determine a rich variety of behaviors among which is an unexpected enhancement of the inelastic diffusion. 
Giulio Costantini, Fabio Cecconi, Umberto Marini-Bettolo-Marconi