Oscillatory instability in a driven granular gas

TL;DR

This paper reports the discovery of an oscillatory instability in a driven granular gas system, supported by theory and simulations, revealing a stripe-shaped cluster oscillating due to inelastic collisions exceeding a critical threshold.

Contribution

The study identifies and characterizes an oscillatory instability in a driven granular gas, combining linear stability analysis with molecular dynamics simulations.

Findings

Instability occurs when inelasticity exceeds a critical value.

Cluster exhibits stripe-shaped oscillations.

Oscillation frequency matches theoretical predictions.

Abstract

We discovered an oscillatory instability in a system of inelastically colliding hard spheres, driven by two opposite "thermal" walls at zero gravity. The instability, predicted by a linear stability analysis of the equations of granular hydrodynamics, occurs when the inelasticity of particle collisions exceeds a critical value. Molecular dynamic simulations support the theory and show a stripe-shaped cluster moving back and forth in the middle of the box away from the driving walls. The oscillations are irregular but have a single dominating frequency that is close to the frequency at the instability onset, predicted from hydrodynamics.