Hydrodynamic theory for dissipative hard spheres with multi-particle   interactions
  Extensions to kinetic theory and hydrodynamic models are proposed that account for the existence of multi-particle contacts. In the presence of multi-particle contacts (involving elastic, reversible, potential contact energy), dissipation of the translational (kinetic) energy is reduced and a class of different models lead to deviations from the classical inelastic hard sphere (IHS) homogeneous cooling state (HCS), as examined here. The theoretical results are found to be in perfect agreement with the numerical simulations. 
Stefan Luding (1,2) and Alexander Goldshtein (3) ((1) ICA1, Stuttgart,   Germany, (2) DCT TUDelft, Netherlands, (3) Haifa, I...