Non-Gaussian velocity distribution function in a vibrating granular bed

The simulation of granular particles in a quasi-two-dimensional container under 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 friction force. A Langevin equation with Coulomb friction is proposed to describe the motion of such a system.

将准二维容器中垂直振动下的颗粒粒子模拟作为颗粒气体的一种可通过实验实现的模型进行研究。速度分布函数在振动过程中遵循类指数函数，在自由冷却状态下偏离指数函数。可以确定这种类指数分布函数是由库仑摩擦力产生的。提出了一个带有库仑摩擦的朗之万方程来描述这样一个系统的运动。