Self-diffusion anlaysis in a vibrated granular bed

摘要

The influences of flow parameters on self-diffusion in a vibrated granular bed were studied by simulation and experiment. Employing image processing technology and a particle tracking method, the local displacements and velocities of particles were measured. The self-diffusion coefficients were determined from the history of particles’ diffusive displacements. Discrete element method simulation was performed to calculate the particles’ self-diffusive displacements. The simulation results were compared to the experimental tests. The flow behavior of convection rolls in a vibrated bed occurred by the particles’ self-diffusion induced by the energy input from vertical external vibration. The velocity fluctuations. granular temperature and self-diffusions were anisotropic with greatest components in the vertical direction. The dependence of the diffusion coefficients on the dimensionless acceleration amplitude. vibration amplitude. vibration frcquency. velocity fluctuations, granular temperature. vibration x elocitv. restitution coefficient and solid fraction are discussed.