Granular shear experiments in a double-split bottom cell geometry

Abstract Granular material with different particle shapes is exposed to continuous shear in a cylindrical shell with a special double-shear geometry. Instead of the classical split-bottom cell with a moving disk, we use a rotating ring at the bottom, with the central and peripheral parts of the bottom plate fixed in a static position. Then, two shear zones are formed with different radii of curvature and qualitatively different features. We compare the behavior of spherical grains to that of elongated spherocylinders, and find significant differences in the formation of secondary flow structures.