Temperature Anisotropy in a Driven Granular Gas

TL;DR

This paper investigates temperature anisotropy in a driven granular gas, showing that energy input direction leads to higher temperature in that direction due to inelastic collisions, supported by an analytical model and simulations.

Contribution

It introduces an analytical model explaining temperature anisotropy in driven granular gases, validated by molecular dynamics simulations.

Findings

Temperature in the energy input direction exceeds other directions.

Anisotropy arises from inelastic collisions and wall interactions.

Non-isotropic driving causes steady-state temperature anisotropy.

Abstract

When smooth granular material is fluidized by vertically shaking a container, we find that the temperature in the direction of energy input always exceeds the temperature in the other directions. An analytical model is presented which shows how the anisotropy can be traced back to the inelasticity of the interparticle collisions and the collisions with the wall. The model compares very well with molecular dynamics simulations. It is concluded that any non-isotropic driving of a granular gas in a steady state necessarily causes anisotropy of the granular temperature.