Impact of high-energy tails on granular gas properties

TL;DR

This paper investigates how the overpopulated high-energy tails in the velocity distribution of granular gases affect their kinetic properties, especially the cooling behavior, and introduces a new approach to quantify this influence.

Contribution

It develops a novel method to quantify the high-energy tail and analyzes its impact on granular gas properties, addressing a gap in existing theoretical understanding.

Findings

Overpopulated high-energy tails influence cooling rates.

Velocity distribution relaxes anomalously slowly.

New approach quantifies tail effects on kinetic properties.

Abstract

The velocity distribution function of granular gases in the homogeneous cooling state as well as some heated granular gases decays for large velocities as $f\propto\exp(- {\rm const.} v)$. That is, its high-energy tail is overpopulated as compared with the Maxwell distribution. At the present time, there is no theory to describe the influence of the tail on the kinetic characteristics of granular gases. We develop an approach to quantify the overpopulated tail and analyze its impact on granular gas properties, in particular on the cooling coefficient. We observe and explain anomalously slow relaxation of the velocity distribution function to its steady state.