ABSTRACT
In using the event-driven method there are two problems. The first one is inelastic collapse and the other is making a rough surface on bottom.
All particles after some collisions lose their energy and accumulate on the bottom and make a dense network of grains, so the number of collisions per unit time will diverge, that is inelastic collapse (Luding & McNamara 1998) occurs. Because of the finite precision of the computer, multiparticle collisions can occur. For handling inelastic collapse we use the TC model with tc = 10−4t0. This means that if a particle experiences two collisions separated by a time less than tc, the second collision occurs without loss of energy. This is sufficient to prevent inelastic collapse.
