A non-standard statistical approach to the silo discharge

We present molecular dynamics simulations of the beginning of a silo discharge by gravity. The evolution of the velocity profile and the probability density functions for the displacements of the grains are obtained. These PDFs reveal non-gaussian statistics and superdiffusive behavior similar to that observed in some experiments. We propose an analytical expression for the PDFs and an explanation for its dynamical origin in connection with the ideas of the "spot" model and non-extensive thermodynamics.