Phase diagram of van der Waals-like phase separation in a driven granular gas

TL;DR

This paper uses granular hydrostatics equations to map the phase diagram of van der Waals-like phase separation in a driven granular gas, analyzing critical points, spinodal lines, and finite size effects.

Contribution

It provides the first detailed phase diagram of a driven granular gas, including analytical and numerical analysis of critical phenomena and finite size effects.

Findings

Determined the spinodal line and critical point analytically.

Showed finite size effects suppress phase separation.

Identified transition from supercritical to subcritical bifurcation.

Abstract

Equations of granular hydrostatics are used to compute the phase diagram of the recently discovered van der Waals-like phase separation in a driven granular gas. The model two-dimensional system consists of smooth hard disks in a rectangular box, colliding inelastically with each other and driven by a "thermal" wall at zero gravity. The spinodal line and the critical point of the phase separation are determined. Close to the critical point the spinodal and binodal (coexistence) lines are determined analytically. Effects of finite size of the confining box in the direction parallel to the thermal wall are investigated. These include suppression of the phase separation by heat conduction in the lateral direction and a change from supercritical to subcritical bifurcation.