On dense granular flows

TL;DR

This paper synthesizes experimental and simulation data on dense granular flows across various geometries to identify key parameters, flow regimes, and challenges in defining a unified rheology for such materials.

Contribution

It provides a comprehensive comparison and analysis of steady uniform granular flow data from multiple experiments and simulations, highlighting robust features and flow regimes.

Findings

Identification of relevant dimensionless parameters

Classification of different flow regimes

Highlighting the complexity of defining a single rheology

Abstract

The behaviour of dense assemblies of dry grains submitted to continuous shear deformation has been the subject of many experiments and discrete particle simulations. This paper is a collective work carried out among the French research group GDR Milieux Divis\'es. It proceeds from the collection of results on steady uniform granular flows obtained by different groups in six different geometries both in experiments and numerical works. The goal is to achieve a coherent presentation of the relevant quantities to be measured i.e. flowing thresholds, kinematic profiles, effective friction, etc. First, a quantitative comparison between data coming from different experiments in the same geometry enforces the robust features in each case. Second, a transversal analysis of the data across the different configurations, allows us to identify the relevant dimensionless parameters, the different flow regimes and to propose simple interpretations. The present work, more than a simple juxtaposition of results, underlines the richness of granular flows and enhances the open problem of defining a single rheology