First-order phase transition and the equation of state in a 2D granular fluid

TL;DR

This paper provides experimental evidence of a first-order phase transition in a 2D granular fluid, showing a discontinuous change in density and temperature, with the equation of state aligning with theoretical predictions.

Contribution

It demonstrates the occurrence of a first-order freezing/melting transition in a nonequilibrium 2D granular system with detailed experimental validation.

Findings

Discontinuous change in density and temperature at transition

Hysteresis observed depending on particle number

Equation of state matches theoretical models

Abstract

We present experimental evidence for a first-order freezing/melting phase transition in a nonequilibrium system -- an oscillated two-dimensional isobaric granular fluid. The steady-state transition occurs between a gas and a crystal and is characterized by a discontinuous change in both density and temperature. It is suppressed if the number of particles is incommensurate with the cell size, shows rate-dependent hysteresis, and obeys the Lindemann criterion for melting. Further, the measured equation of state both above and below the phase transition compares well with theory.