Self-diffusion in granular gases: An impact of particles' roughness

TL;DR

This paper investigates how particles' roughness affects self-diffusion in granular gases, developing an analytical theory and validating it with molecular dynamics simulations, revealing the impact of restitution coefficients.

Contribution

The paper introduces an analytical model for self-diffusion in granular gases considering particle roughness and non-Maxwellian velocity distributions, validated by simulations.

Findings

Theoretical diffusion coefficients agree well with simulation data.

Particle roughness significantly influences self-diffusion behavior.

Dependence of diffusion on restitution coefficients is quantitatively characterized.

Abstract

An impact of particles' roughness on the self-diffusion coefficient in granular gases is investigated. For a simplified collision model where the normal and tangential restitution coefficients are assumed to be constant we develop an analytical theory for the diffusion coefficient, which takes into account non-Maxwellain form of the velocity-angular velocity distribution function. We perform molecular dynamics simulations for a gas in a homogeneous cooling state and study the dependence of the self-diffusion coefficient on restitution coefficients. Our theoretical results are in a good agreement with the simulation data.