Homogeneous Cooling with Repulsive and Attractive Long-range Interactions

In granular matter, consisting of discrete particles, long-range interactions imply that each of the particles is interacting with all others. For many charged granular materials with Coulomb repulsion or large-scale gravitationally attractive systems, a Molecular Dynamics environment is developed. In granular systems with long-range interaction forces and dissipative collisions, both effects can lead to large-scale structure formation, whereas already dissipation alone leads to ever growing clusters. For our three-dimensional mono-charged dissipative homogeneous systems we present the effect of both repulsive and attractive mutual long-range forces and make an attempt to predict the collision frequency and the temperature decay in the system by means of a modified pseudo-Liouville operator formalism. The theoretical predictions are in perfect agreement with the simulations, but only in the limit of low density and for not too strong interaction potential enrgy.