Edwards thermodynamic framework controls density segregation in cyclically sheared granular materials

TL;DR

This paper demonstrates that granular density segregation under cyclic shear can be explained by an Edwards thermodynamic framework, linking segregation behavior to an effective temperature derived from statistical mechanics.

Contribution

It introduces a thermodynamic framework based on Edwards' ensemble to explain density segregation in cyclically sheared granular materials, supported by experimental evidence.

Findings

Segregation temperature matches Edwards' compactivity across conditions.

Granular segregation can be explained by an effective thermodynamic model.

Height distributions at steady state align with free energy minimization.

Abstract

Using X-ray tomography, we experimentally investigate granular segregation phenomena in a mixture of particles with different densities under quasi-static cyclic shear. We quantitatively characterize their height distributions at steady states by minimizing effective free energy based on a segregation temperature that captures the competition between the mixing entropy and gravitational potential energy. We find this temperature coincides with Edwards' compactivity within error under various pressures and cyclic shear amplitudes. Therefore, we find that granular segregation in quasi-static conditions can be fundamentally explained by an effective granular thermodynamic framework including real energy terms based on the Edwards statistical ensemble.