Wide and universal shear zones in granular matter

Dr. D. Fenistein, Kamerlingh Onnes Laboratorium,  Universeit van Leiden

We present experiments in which wide and universal shear zones are created in the bulk of granular material (Denis Fenistein & Martin van Hecke, Nature 425, 256 2003).  The modification of a Couette cell whose bottom is split at a given radius allows the observation of bulk shear zones that strongly contrast the usual picture of granular matter flow where narrow particle-dependent shear bands are localized at a
boundary. We focus on the description of the universal Gaussian strain rate profiles. The position and width of the shear zones appear to be uncorrelated and can be tuned by the experimental geometry and the particle properties.