Measurement of granular temperature and velocity profile of granular flow in silos

In this paper we report experimental results on the granular temperature and velocity profile of glass beads in steady-state flow inside a flat-bottomed silo. We found that the dynamics of the granular system during the discharge is stable on the mesoscopic scale. In particular, the ordered directional movement of particles can occur near the orifice. In addition, the correlation between the granular temperature distribution and velocity vector field is opposite in the radial and axial directions. According to the kinetic model, the main cause for the reversal of spatial correlation is that the intensity of the particle diffusion decrease with the decrease of silo height. This highlights a surprising and unrecognized role that the diffusion motion of particles plays in energy dissipation for hopper flow.