Coarse-grained discrete element method for granular shear flow

Abstract Powder mixing process plays an important role in chemical industries. In manufacturing sectors, there is a great demand for developing a coarse-grained model of a discrete element method (DEM) to perform DEM simulations of powder mixing processes at the manufacturing scale. Herein, we present a coarse-grained method for granular shear flow (CGSF). The CGSF was developed for a powder mixing process with a dense granular shear flow. The CGSF was built to match four types of energies between the coarse-grained and original particles under a granular shear flow. Based on the energy matching concept, scaling laws for the contact force parameters were derived. A scaling law for the sliding friction coefficient was derived considering the sliding friction damping between the original particles in the intra-coarse-grained region as well as those in the inter-coarse-grained regions. The CGSF was applied to the coarse-grained DEM simulation of a rotating drum mixer, and its performance was evaluated. The coarse-grained DEM simulation with the CGSF exhibited a result quite similar to the original case in terms of the particle velocity, kinetic energy, and degree of particle mixing. The most critical scaling was of the sliding friction coefficient, suggesting the significance of the scaling law proposed for the sliding friction. In conclusion, we demonstrated the effectiveness of the proposed CGSF for the coarse-grained DEM simulation of a powder mixing process with a dense granular shear flow.