Rheology of dense granular flows for elongated particles

Abstract

We study the rheology of dense granular flows for frictionless spherocylinders by means of 3D numerical simulations. As in the case of spherical particles, the effective friction $\mu$ is an increasing function of the inertial number $I$, and we systematically investigate the dependence of $\mu$ on the particle aspect ratio $Q$, as well as that of the normal stress differences, the volume fraction and the coordination number. We show in particular that the quasi-static friction coefficient is non-monotonic with $Q$: from the spherical case $Q=1$, it first sharply increases, reaches a maximum around $Q\simeq 1.05$, and then gently decreases, reaching back its initial value for $Q\simeq 2$. We provide a microscopic interpretation for this unexpected behavior through the analysis of the distribution of dissipative contacts around the particles: as compared to spheres, slightly elongated grains enhance contacts in their central cylindrical band, whereas at larger aspect ratios particles tend to align and dissipate by preferential contacts at their hemispherical caps.

5 pages, 5 figures

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• Depletion Forces in Athermally Sheared Mixtures of Frictionless Disks and Rods in Two Dimensions
• Packings of frictionless spherocylinders
• Transverse vortices induced by modulated granular shear flows of elongated particles
• Orientational arrest in dense suspensions of elliptical particles under oscillatory shear flows
• Directional shear-jamming
• Dynamic Phases and Combing Effects for Elongated Particles Moving Over Quenched Disorder
• Translational and rotational velocities in shear-driven jamming of ellipsoidal particles
• Shear flow of frictional spheroids: Comparison between elongated and flattened particles
• Collective alignment controls rotation frustration in granular flows of elongated particles
• Start-up shear of spherocylinder packings: effect of friction