Shear viscosity scaling of granular suspensions across dilute to dense regimes

TL;DR

This paper presents a unified scaling framework for the shear viscosity of granular suspensions across dilute and dense regimes, validated through extensive experiments and simulations, revealing a strong correlation between inverse relative viscosity and shear stress.

Contribution

It introduces a novel dilute-dense transitional solid fraction and a universal scaling solution that incorporates both solid fraction and shear rate dependencies.

Findings

Strong correlation between inverse relative viscosity and shear stress.

Universal scaling solution for suspension viscosity across regimes.

Identification of a dilute-dense transition mechanism.

Abstract

In this letter, following an extensive experimental validation, we perform constant-volume shearing simulations of non-Brownian granular suspensions using the discrete element method coupled with the lattice Boltzmann method. We choose a wide range of solid fractions, shear rates, fluid viscosities, particle sizes, and inter-particle frictional coefficients to obtain a scaling solution for the viscous behavior of suspensions in both dilute and dense regimes. This letter demonstrates that, with a proposed dilute-dense transitional solid fraction, $\phi_d$, there exists a strong correlation between the inverse relative viscosity and the shear stress. This work incorporates both the $\phi$-dependence and the $\dot{\gamma}$-dependence of suspension viscosity in a universal framework, which provides a scaling solution for granular suspensions across dilute and dense regimes and sheds light on the dilute-dense transition mechanisms.