Flow and rheology of frictional elongated grains

TL;DR

This study investigates the rheology of frictional elongated grains using DEM simulations, revealing non-monotonic effective friction behavior related to particle aspect ratio and friction coefficient, with insights into microscopic origins.

Contribution

It introduces a detailed DEM analysis of elongated granular particles, uncovering novel non-monotonic friction behavior and microscopic mechanisms affecting rheology.

Findings

Effective friction varies non-monotonically with aspect ratio for low friction coefficients.

Normal stress differences depend on particle-level quantities.

Velocity fluctuations are influenced by dissipation regimes.

Abstract

The rheology of a 3-dimensional granular system consisting of frictional elongated particles was investigated by means of discrete element model (DEM) calculations. A homogenous shear flow of frictional spherocyliders was simulated, and a number of rheological quantities were calculated. In the framework of the $\mu(I)$ rheology, the effective friction was found to be a non-monotonic function of the aspect ratio for interparticle friction coefficient $\mu_p \lesssim 0.4$, while it was an increasing function for larger $\mu_p$. We reveal the microscopic origin of this peculiar non-monotonic behavior. We show the non-trivial dependence of the velocity fluctuations on the dissipation regime, and trace back the behavior of the normal stress differences to particle-level quantities.