Velocity Profile Geometries and Granular Temperature Distributions in Very Dense Granular Flows

Abstract

AbstractUnderstanding the motion of particles in very dense granular flows is crucial for comprehending the dynamics of many geological phenomena, and advancing our knowledge of granular material physics. We conduct transparent ring shear experiments to directly observe the granular motion under relatively high‐pressure conditions, and find that the granular velocity non‐linearly decays, forming an approximately 7‐particle‐diameter‐thick localized shear band. A fitting curve underlying non‐local physics can be used to well predict velocity profile geometries that are almost independent of normal stress and shear velocity. Moreover, experimental results show monotonically decreasing granular kinetic temperature, which may be caused by energy dissipation due to more inelastic contacts under high confining pressures. The variation of granular temperature will significantly influence the local yield stress and rheological properties, which may lead to inhomogeneous fluidity of the material and thus to shear localization in very dense granular flows.