GRANULAR DYNAMICS IN A SWIRLED ANNULUS

A swirled annular channel is introduced that is suited to study the dy namics of granular arrays. We uncover the mechanism that is responsibl e for the change of the sense of rotation of a two-dimensional cluster of spheres that is excited by horizontal, orbital shaking. Experiment al investigations are presented that show the influence of packing den sity, channel width, driving frequency, and material parameters. We co mpare this with a simple one-dimensional model. It is seen that the sy stem is governed by single binary collisions that give rise to global behavior, namely, a corotating or counterrotating motion of the cluste r. [S1063-651X(98)11910-4].