Flow-induced shear instabilities of cohesive granulates

TL;DR

This paper develops a multi-scale analytical framework to determine the shear-induced fluidization threshold of cohesive granulates, accounting for packing structure and porosity effects, with implications for understanding granular stability under flow.

Contribution

It introduces a closed-form analytical expression for the shear instability threshold of cohesive granular packings, integrating structural and dynamical factors.

Findings

Derived an analytical expression for the fluidization threshold.

Quantified the influence of packing orientation and porosity.

Validated the model for regular mono-disperse spherical grains.

Abstract

In this work we use a multi-scale framework to calculate the fluidization threshold of three-dimensional cohesive granulates under shear forces exerted by a creeping flow. A continuum model of flow through porous media provides an analytical expression for the average drag force on a single grain. The balance equation for the forces and a force propagation model are then used to investigate the effects of porosity and packing structure on the stability of the pile. We obtain a closed-form expression for the instability threshold of a regular packing of mono-disperse frictionless cohesive spherical grains in a planar fracture. Our result quantifies the compound effect of structural (packing orientation and porosity) and dynamical properties of the system on its stability.