SIMULATION OF GRANULAR MEDIA

The flow of granular material, like sand, presents many intriguing effects in particular when it is shaken, poured or sheared. Here, the granular medium is modelled by a packing of elastic spheres and simulated via molecular dynamics. Dissipation of energy and shear friction at collisions are included. The onset of fluidization can be determined and is in good agreement with experiments. On a vibrating plate we observe the formation of convection cells due to walls or amplitude modulations. Density and velocity profiles on conveyor belts are measured and the influence of an obstacle discussed. We mention various types of rheology for flow down an inclined chute or through a pipe and outflowing containers. We also briefly sketch a thermodynamic formalism for granular material.