Shear thickening in granular suspensions: inter-particle friction and dynamically correlated clusters

TL;DR

This study investigates how frictional interactions and the formation of particle clusters lead to shear thickening in concentrated granular suspensions, contrasting with shear-thinning behavior in frictionless systems.

Contribution

It demonstrates that shear thickening arises from frictional dissipation and correlated particle clusters, providing a scaling law linking viscosity and cluster size.

Findings

Shear thickening is driven by frictional energy dissipation.

Dynamically correlated clusters of particles form and grow during shear thickening.

Viscosity scales with the square of the correlation length, η ∼ ξ².

Abstract

We consider the shear rheology of concentrated suspensions of non-Brownian frictional particles. The key result of our study is the emergence of a pronounced shear-thickening regime, where frictionless particles would normally undergo shear-thinning. We clarify that shear thickening in our simulations is due to enhanced energy dissipation via frictional inter-particle forces. Moreover, we evidence the formation of dynamically correlated particle-clusters of size $\xi$, which contribute to shear thickening via an increase in \emph{viscous} dissipation. A scaling argument gives $\eta\sim \xi^2$, which is in very good agreement with the data.