Langevin Simulation of Non-Uniform Granular Gases

We present and study a fractal model of a non-uniform granular system for the first time, based on which we numerically solve the dynamics actions in the system successfully in one-dimensional case. The multi-mixture is composed of N different particles, whose granularity distribution has the fractal characteristic. The particles subject to inelastic mutual collisions and obey to Langevin equation between collisions. Far from the equilibrium, i.e., the given typical relaxation time τ of the driving Brownian process is much larger than the mean collision time τ_c, the results of simulation indicate that the degree of inhomogeneity in the granularity distribution signed by the fractal dimension D of size distribution has great influences on the dynamics actions of the system. The velocity distribution deviates obviously from the Gaussian distribution and the particles cluster more pronounced with the larger value of D in the system. The velocity distribution and spatial clusterization changing with D are presented.