Computer simulations for a scholastic theory of granular drainage

Abstract

There is a surprising lack of good models for granular flow. In 2002, Bazant proposed a new stochastic kinematic model of granular drainage from a silo. The new model rests on the notion that flow in the silo is caused by the migration of extended regions of excess interstitial space upward from the orifice at the bottom. An implementation of this model with the purpose of simulating the behavior of particles in the silo was developed by the author, and several results were obtained using simulations carried out with this implementation. As regards particle streamlines, average velocity profiles, predictions of particle mixing and of particle diffusivity, it was found that qualitative and quantitative agreement with experiments was excellent, in particular for a specific version of the implementation. This version uses a self-correlated random walk to describe the motion of the excess interstitial space through the silo. The model can also be used to make predictions about many other features of the granular flow (such as granular temperature), that are not as accessible through experiment's, and for which empirical behavior is not well known. In particular, the implementation of the model developed in this work can be used to simulate three dimensional flow, whereas existing experimental techniques are limited to observing two dimensions.