The stadium shear device: A novel apparatus for studying dense granular flows

Abstract

We present a new experimental apparatus for studying dense granular flows. The device is able to produce plane shear flow over large deformations by utilising a novel stadium geometry. Both the grainscale kinematics and the macroscopic stresses can be captured. We report results from a set of experiments which confirm the existence of transient, rotational motions within such flows and reveal the corresponding S shaped velocity profiles, which are not predicted by the local constitutive laws. By borrowing from the concept of eddy viscosity in turbulent boundary layers, we propose a model which suggests this is a result of the non-local behaviour of the material and the proximity to the wall. This new device allows for the experimental examination of dense granular flows in a way not previously possible while our non-local model provides an insight into the flow rheology. © 2013 AIP Publishing LLC.