Couette flows of a granular monolayer—an experimental study

Abstract

An experimental study concerning rapid flows of granular materials in a two-dimensional planar granular Couette flow apparatus is performed. The device is capable of generating particulate flows in the grain-inertia regime at different shearing rates and solid volume fractions. Multi-color spherical glass particles are sheared across an annular test-section for several wall angular velocities. A video recorder is used to record the motion of particles and consecutive images are stored and analyzed by an image processing technique for evaluating individual grain velocities. Experimental data for the mean velocity, the root-mean-square (RMS) fluctuation velocity components and the solid volume fraction profiles are obtained. The resulting mean velocity profiles have a roughly linear variation for the range of solid volume fractions and shear rates studied. The solid volume fraction profiles exhibit non-uniform variations with the highest concentration occurring near the center of the shearing cell. The RMS fluctuation velocities are roughly constant, with the streamwise fluctuation being somewhat larger than the cross-stream direction. The experimentally measured flow properties are in reasonable agreement with the earlier theoretical and simulation results.