Order-disorder transition in swirled granular disks

TL;DR

This study uses simulations to analyze how external driving influences order-disorder transitions in swirled granular disks, revealing phase behavior and differences between dry and wet particles.

Contribution

It provides a systematic simulation-based analysis of local order formation and phase transitions in swirled granular disks, including wet and dry cases, with a focus on the emergence of hexagonal and square orders.

Findings

Large hexagonal clusters form at intermediate energies.

Wet particles achieve higher hexagonal order than dry.

Transition characterized by emergence of square local order.

Abstract

We study the order-disorder transition of horizontally swirled dry and wet granular disks by means of computer simulations. Our systematic investigation of the local order formation as a function of amplitude and period of the external driving force shows that a large cluster of hexagonally ordered particles forms for both dry and wet granular particles at intermediate driving energies. Disordered states are found at small and large driving energies. Wet granular particles reach a higher degree of local hexagonal order, with respect to the dry case. For both cases we report a qualitative phase diagram showing the amount of local order at different state points. Furthermore we find that the transition from hexagonal order to a disordered state is characterised by the appearance of particles with square local order.