Non-Gaussian Velocity Distribution Function in a Vibrating Granular Bed

Abstract

The simulation of granular particles in a quasi two-dimensional container under the vertical vibration as an experimental accessible model for granular gases is performed. The velocity distribution function obeys an exponential-like function during the vibration and deviates from the exponential function in free-cooling states. It is confirmed that this exponential-like distribution function is produced by Coulomb's friction force. A Langevin equation with Coulomb's friction is proposed to describe the motion of such the system.Comment: 4 pages, 4 figures. to be published in Journal of Physical Society of Japan Vol.73 No.