Role of roughness on the hydrodynamic homogeneous base state of inelastic spheres

Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Feb;89(2):020202. doi: 10.1103/PhysRevE.89.020202. Epub 2014 Feb 18.

Abstract

A gas of inelastic rough spheres admits a spatially homogeneous base state which turns into a hydrodynamic state after a finite relaxation time. We show that this relaxation time is hardly dependent on the degree of inelasticity but increases dramatically with decreasing roughness. An accurate description of translational-rotational velocity correlations at all times is also provided. At a given inelasticity, the roughness parameter can be tuned to produce a huge distortion from the Maxwellian distribution function. The results are obtained from a Grad-like solution of the Boltzmann-Enskog equation complemented by Monte Carlo and molecular dynamics simulations.