Rheology of dense granular suspensions across flow regimes Elisabeth Guazzelli

Abstract: Dense granular suspensions, consisting of concentrated mixtures of non-Brownian particles suspended in a liquid, are ubiquitous in many natural phenomena (e.g. landslides, debris flows and sediment transport) and industrial processes (e.g. concrete and pastes). Their rheology is not fully understood, and the establishment of a unified theoretical framework for different flow regimes remains a challenge. The present work describes rheological measurements of granular suspensions in the dense regime, performed at imposed volume fractions, but also at imposed values of particle normal stress. It proposes a unified granular rheology over the viscous to inertial flow regime based on the superposition of inertial and viscous stress scales. This granular rheology, found for suspensions of hard spheres, can be extended to a soft granular rheology for soft particles. This soft granular rheology leads to an approximate collapse of the rheological data into two branches when scaled with the distance to jamming, similar to what is found for viscous soft colloids. The findings aim to unify granular and suspension flows, providing a framework for understanding complex particulate systems in engineering and natural contexts. ​

This work was carried out with Pascale Aussillous, Chong-Wei Hong, Olivier Pouliquen (Aix-Marseille Université, CNRS, IUSTI, Marseille, France), with Alireza Khodabakhshi, Sudarshan Konidena, Franco Tapia, Bernhard Vowinckel (TU Dresden, Dresden, Germany), and with Mie Ichihara (Earthquake Research Institute, The University of Tokyo, Tokyo, Japan).