Energy non-equipartition in systems of inelastic, rough spheres

TL;DR

This paper investigates how energy distributes between translational and rotational modes in systems of inelastic, rough spheres, revealing non-equipartition effects influenced by particle roughness and dissipation, supported by calculations and simulations.

Contribution

It provides a unified and simplified approach to analyze energy ratios in inelastic rough spheres, encompassing various flow conditions and emphasizing boundary effects.

Findings

Energy ratio depends mainly on particle roughness in stationary flows.

In freely cooling flows, the ratio also strongly depends on normal dissipation.

Boundary energy flux significantly influences energy distribution.

Abstract

We calculate and verify with simulations the ratio between the average translational and rotational energies of systems with rough, inelastic particles, either forced or freely cooling. The ratio shows non-equipartition of energy. In stationary flows, this ratio depends mainly on the particle roughness, but in nonstationary flows, such as freely cooling granular media, it also depends strongly on the normal dissipation. The approach presented here unifies and simplifies different results obtained by more elaborate kinetic theories. We observe that the boundary induced energy flux plays an important role.