Rotational statistics in granular flows of smooth cylindrical particles

We report the results of an experiment to investigate the energy dissipation in the rotational degree of freedom for smooth cylindrical particles in a driven granular flow. The 2D geometry and the experimental design allow for the measurement of three degrees of freedom in the dynamics: the rotational degree of freedom for the disks to spin about their cylindrical axes as well as the two translational degrees of freedom of the particles within the cell. The rotational velocity statistics demonstrate non-Gaussian behavior as well as a significant amount of energy being dissipated through the flow via the tangential friction between particles. These results are significant in that many driven granular experiments use smooth cylindrical or spherical particles to investigate granular dynamics, but the contribution to the dynamics from the rotational degrees of freedom is often unmeasured.