Segregation Mechanisms in a Model of an Experimental Binary Granular   Mixture
  A simple phenomenological model of a binary granular mixture is developed and investigated numerically. We attempt to model the experimental system of [1,2] where a horizontally vibrated binary monolayer was found to exhibit a transition from a mixed to a segregated state as the filling fraction of the mixture was increased. This model is found to reproduce much of the experimentally observed behaviour, most importantly the transition from the mixed to the segregated state. We use the model to investigate granular segregation mechanisms and explain the experimentally observed behaviour. 
George C.M.A. Ehrhardt, Andrew Stephenson, Pedro M. Reis