Self-diffusion in granular gases

TL;DR

This paper investigates how the velocity dependence of the restitution coefficient affects self-diffusion in granular gases, revealing different time-dependence behaviors and their implications for the properties of cooling granular gases.

Contribution

It introduces the impact of velocity-dependent restitution coefficient on self-diffusion, contrasting it with constant restitution models, and discusses resulting effects on granular gas dynamics.

Findings

Velocity dependence leads to power-law diffusion behavior.

Constant restitution results in logarithmic slow spreading.

Differences influence the cooling and transport properties of granular gases.

Abstract

The coefficient of self-diffusion for a homogeneously cooling granular gas changes significantly if the impact-velocity dependence of the restitution coefficient $\epsilon$ is taken into account. For the case of a constant $\epsilon$ the particles spread logarithmically slow with time, whereas the velocity dependent coefficient yields a power law time-dependence. The impact of the difference in these time dependences on the properties of a freely cooling granular gas is discussed.