# Driven and undriven states of multicomponent granular gases of inelastic and rough hard disks or spheres

## TL;DR

This paper compares the relaxation dynamics and nonequipartition effects in multicomponent granular gases of inelastic and rough disks or spheres, under both free cooling and driven conditions, revealing differences based on particle shape and system state.

## Contribution

It provides a detailed analysis of how particle shape and driving conditions influence energy distribution and relaxation in granular gas mixtures, including the novel study of the mimicry effect.

## Key findings

- Disks relax faster than spheres in collision number.
- Rotational-translational nonequipartition is stronger in disks in undriven systems.
- Component-component nonequipartition is higher for spheres.

## Abstract

Starting from a recent derivation of the energy production rates in terms of the number of translational and rotational degrees of freedom, a comparative study on different granular temperatures in gas mixtures of inelastic and rough disks or spheres is carried out. Both the homogeneous freely cooling state and the state driven by a stochastic thermostat are considered. It is found that the relaxation number of collisions per particle is generally smaller for disks than for spheres, the mean angular velocity relaxing more rapidly than the temperature ratios. In the asymptotic regime of the undriven system, the rotational-translational nonequipartition is stronger in disks than in spheres, while it is hardly dependent on the class of particles in the driven system. On the other hand, the degree of component-component nonequipartition is higher for spheres than for disks, both for driven and undriven systems. A study of the mimicry effect (whereby a multicomponent gas mimics the rotational-translational temperature ratio of a monocomponent gas) is also undertaken.