Granular Brownian motion

Abstract

We study the stochastic motion of an intruder in a dilute driven granular\ngas. All particles are coupled to a thermostat, representing the external\nenergy source, which is the sum of random forces and a viscous drag. The\ndynamics of the intruder, in the large mass limit, is well described by a\nlinear Langevin equation, combining the effects of the external bath and of the\n"granular bath". The drag and diffusion coefficients are calculated under few\nassumptions, whose validity is well verified in numerical simulations. We also\ndiscuss the non-equilibrium properties of the intruder dynamics, as well as the\ncorrections due to finite packing fraction or finite intruder mass.\n