Origins of granular memory in model sandpiles

Abstract

We describe a lattice model for intermittent flow in granular materials. This model includes degrees of freedom, related to lattice grain orientations, that are additional to those associated with the coupled dynamics of columns of lattice grains. We have explored the development of granular structures in model piles and shown that the surface dynamics of lattice grains is strongly linked to relaxations of granular structures in the pile. The coupling is shown to lead to two distinct avalanche morphologies in model piles that have been disturbed from their steady state. The change of behaviour is explained in terms of the statistical properties of surface instabilities.