Intuition tells us that a rolling or spinning sphere on a table will eventually stop due to the presence of friction. Nonetheless, rolling and twisting friction are often neglected in particle simulations. Rolling and twisting friction are important in granular rheology, where the flow field induces rotations. Granular rheology is simulated using particle-based, discrete element simulations with sliding, rolling and twisting friction in different configurations, including chute flow and bulk-like stress-controlled shear. Stress differences, stress ratios and inertial numbers are used to characterize the rheological behavior for different friction states. The increase in critical stress to flow, for bulk-like rheology, and the angle of repose, for chute flow, due to rolling and twisting friction is measured. The fabric tensor is used to characterize the structure of the flowing states. Beyond the contact, normal and tangential fabric tensors, the two rotational fabric tensors, from rolling and twisting friction, are also calculated. Chute flows are further characterized by property profiles perpendicular to the plane.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energyâs National Nuclear Security Administration under contract DE-NA0003525.