INTERACTION LAWS AND THE DETACHMENT EFFECT IN GRANULAR MEDIA

We study granular materials using both event driven (ED) and molecular dynamics (MD) methods. In the MD simulations we implement linear as well as nonlinear forces and also hysteretic interactions. For multiple collisions the two methods show differences: MD calculations lead to weak, whereas ED methods result in rather strong dissipation, as determined through an effective restitution coefficient. Introduction and Background Recent years have seen much effort in understanding granulates, which are assemblies of solid, possibly nonuniform, particles, interacting via contact forces. Summaries of the present knowledge on granular media are given in Refs.[1-2]. These materials display size-segregation, heap formation under vibration and bulk dilatation, as well as density wave formation an