Stochastic Aspects of Granular Flow in Vibrated Beds

Abstract

A stochastic approach has been taken to examine the flow behaviour of particles in a vibrated granular bed. The coordinates of a single grain were determined as a function of time using the technique of positron emission particle tracking. Following a particle for extended periods allowed a detailed representation of the displacement probability density to be built up. This showed that, initially, particles dispersed according to a Gaussian law, but that the variation in the solid fraction of grains, their granular temperature and the presence of walls meant that significant distortions were observed over longer timescales. The determination of the displacement probability density allowed the spatial distribution of the granular temperature and the diffusion coefficient to be measured in both mono- and bi-disperse granular systems.