Thermal fluctuations of granular gas under HCS using two-point kinetic theory

TL;DR

This paper investigates thermal fluctuations in granular gases under homogeneous cooling state using two-point kinetic theory, highlighting deviations from elastic gases due to nonequilibrium effects.

Contribution

It extends two-point kinetic theory to granular gases, quantifying how thermal fluctuations differ from elastic gases under HCS.

Findings

Thermal fluctuations are modified by nonequilibrium moments.

Deviations from elastic gases depend on restitution coefficient.

Theoretical framework for granular gas fluctuations is established.

Abstract

Thermal fluctuations of the granular gas under the homogeneous cooling state (HCS) are estimated using two-point kinetic theory by Tsuge-Sagara. Thermal fluctuations of the elastic gas are modified for the granular gas by nonequilibrium moments, which defines the distribution function under the HCS. The deviations of thermal fluctuations for the granular gas from those for the elastic gas obtained by the fluctuation-dissipation theorem are calculated as a function of the restitution coefficient.