Rheology of dense granular binary mixtures

Dry flow of monodisperse granular systems has enjoyed a rich history of investigation, but the rheological properties of binary mixtures with strong size dispersity are still poorly understood. Here, we perform discrete element modeling simulations with frictionless inter-particle interactions to study dry granular flow of binary mixtures under simple shear in the small inertial number regime. Spherical particles with particle size ratios of up to 16 are considered. We compute the shear stress ratio during steady flow as a function of the particle size ratio and fraction of small particles, and compare our results with identically parametrized monodisperse granular flows. Intriguing variations in the rheology for systematic variations in particle size ratios and small particle volume fractions are examined from microstructural analysis of the coordination number, volume fraction, and the stress partitioning between particles of separate size classes.



Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.