Superheating and melting phenomena of a vibrated granular layer of cubic particles

TL;DR

This study combines experiments and simulations to explore superheating and melting in vibrated granular cubic particles, revealing critical shaking thresholds and phase transition dynamics similar to thermal systems.

Contribution

It demonstrates the applicability of the KJMA equation to describe phase transitions in vibrated granular matter, highlighting the effects of friction and shaking strength.

Findings

Superheating persists below a critical shaking amplitude Gamma_c.

Transition to granular liquid occurs above Gamma_c over a timescale tau.

Friction prolongs superheated state but does not alter scaling laws.

Abstract

We report the combined results of experiments and molecular dynamics simulations conducted to investigate superheating phenomena in vertically vibrated granular matter. Specifically, we consider a system of cubic particles densely packed in a square-lattice array and subjected to different shaking strengths, denoted by Gamma, approaching a critical value Gamma_c. Below Gamma_c, the superheated crystalline array remains indefinitely stable. Above Gamma_c, it transitions progressively into a granular liquid-like state over a Gamma-dependent timescale tau. We show that while an increase in frictional contacts significantly prolongs the lifetime of the superheated crystalline state, it does not play a major role in the scaling laws governing how that lifetime depends on shaking strength. Our findings also show that the transition from the superheated solid to the liquid state in the vibrated system is well described by a Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation, which is commonly used to model phase transformations in thermal systems.