Experimental Study of the Nematic Transition in Granular Spherocylinder Packings under Tapping

TL;DR

This study experimentally investigates the nematic transition in granular spherocylinder packings under tapping, validating theoretical models and providing insights into phase behavior and nucleation in granular systems.

Contribution

It introduces an empirical free energy model that predicts phase transitions, coexistence, and nucleation barriers in tapped granular spherocylinder packings, validated by experiments.

Findings

The free energy model accurately predicts the nematic transition.

Phase coexistence and nucleation barriers match experimental data.

Validation of the Edwards ensemble framework for spherocylinders.

Abstract

Using x-ray tomography, we experimentally investigate the nematic transition in granular spherocylinder packings induced by tapping. Upon the validation of the Edwards ensemble framework in spherocylinders, we introduce an empirical free energy that accounts for the influence of gravity and the mechanical stability requirements specific to granular systems. This free energy can predict not only the correct phase transition behavior of the system from a disordered state to a nematic phase, but also a phase coexistence range and nucleation energy barriers that agree with experimental observations.