Simulations of vibrated granular medium 

with impact velocity dependent  restitution coefficient

  ¹  I.C.P., Universität Stuttgart, 70569 Stuttgart, Germany

² Labo. Physique, ENS Lyon, UMR 5972 CNRS, 46 allée d'Italie, 69007 Lyon, France

We report numerical simulations of strongly vibrated granular materials designed to mimic recent experiments performed in both the presence and the absence of gravity. The coefficient of restitution used here depends on the impact velocity by taking into account both the viscoelastic and plastic deformations of particles, occurring at low and high velocities, respectively. We show that this model with impact-velocity-dependent restitution coefficient reproduces results that agree with experiments. We measure the scaling exponents of the granular temperature, collision frequency, impulse, and pressure with the vibrating piston velocity as the particle number increases. As the system changes from a homogeneous gas state at low density to a clustered state at high density, these exponents are all found to decrease continuously with increasing particle number. All these results differ significantly from classical inelastic hard sphere kinetic theory and previous simulations, both based on a constant restitution coefficient. ©2005 The American Physical Society