van der Waals-like phase separation instability of a driven granular gas in three dimensions

TL;DR

This paper demonstrates that the van der Waals-like phase separation instability observed in two-dimensional driven granular gases also occurs in three dimensions, confirmed by theoretical analysis and molecular dynamics simulations.

Contribution

It extends the understanding of phase separation in driven granular gases from 2D to 3D, showing the persistence of the instability and providing theoretical and simulation validation.

Findings

Phase separation instability occurs in 3D driven granular gases.

Negative compressibility leads to spontaneous symmetry breaking.

Simulations confirm theoretical predictions.

Abstract

We show that the van der Waals-like phase separation instability of a driven granular gas at zero gravity, previously investigated in two-dimensional settings, persists in three dimensions. We consider a monodisperse granular gas driven by a thermal wall of a three-dimensional rectangular container at zero gravity. The basic steady state of this system, as described by granular hydrodynamic equations, involves a denser and colder layer of granulate located at the wall opposite to the driving wall. When the inelastic energy loss is sufficiently high, the driven granular gas exhibits, in some range of average densities, negative compressibility in the directions parallel to the driving wall. When the lateral dimensions of the container are sufficiently large, the negative compressibility causes spontaneous symmetry breaking of the basic steady state and a phase separation instability. Event-driven molecular dynamics simulations confirm and complement our theoretical predictions.