The Liquid-Gas Transition in Granular Matter : a Question of Effective Friction ?

TL;DR

This paper investigates whether a liquid-gas transition exists in granular matter without attractive forces, analyzing rheological differences and microscopic dynamics through models and numerical data.

Contribution

It provides a comparative analysis of models for granular fluids and offers a microscopic interpretation of the transition based on physical time scales.

Findings

Gas and liquid regimes show distinct rheological responses

The transition can be understood through relevant physical time scales

Numerical data supports the proposed microscopic interpretation

Abstract

This work presents a comparative study of the best models available to describe granular fluids in order to investigate the extent to which it makes sense to speak about a liquid-gas transition in a system of particles that present no attractive interactions. It is shown that the gas and the liquid correspond to regimes with clearly distinct rheological responses. A microscopic interpretation of what happens at the transition in terms of the time scales relevant to the various physical processes is also presented and put the test against numerical data. Our work calls for more experiments to test our predictions on real systems.