A Maxwell Construction for Phase Separation in Vibrated Granular Matter?

TL;DR

This study investigates phase separation in vibrated granular matter, demonstrating that a Maxwell construction can predict coexisting phases and pressures despite the system's non-equilibrium nature.

Contribution

It introduces a Maxwell construction approach for phase coexistence in vibrated granular gases, derived from mechanical work minimization, despite the system's non-equilibrium conditions.

Findings

Densities follow a lever rule

Maxwell construction predicts coexisting pressure and densities

Pressure-volume characteristic is not an isotherm

Abstract

Experiments and computer simulations are carried out to investigate ordering principles in a granular gas which phase separates under vibration. The densities of the dilute and the dense phase are found to follow a lever rule. A Maxwell construction is found to predict both the coexisting pressure and binodal densities remarkably well, despite the fact that the pressure-volume characteristic $P(v)$ is not an isotherm. Although the system is far from equilibrium and energy conservation is strongly violated, we derive the construction from the minimization of mechanical work and fluctuating particle currents.