Velocity fluctuations inside two and three dimensional silos

In this paper we report experimental and numerical results on the velocity fluctuations of grains inside silos. Although simple models exist for the stationary and continuous approximation of the flow, the variability at the microscopic level (both ensemble averages and the fluctuations of individual particles around the average) reveal non-Gaussian statistics that resist a straightforward treatment. We also show that decreasing the orifice size causes an increase in the relative amplitude of the velocity fluctuations, meaning that the intermittency grows bigger.