Development of particle stress model for MP-PIC approach

Computational Fluid Dynamics (CFD) - Discrete Element Method (DEM) simulations are widely used to investigate gas-solid flow behavior in fluidized beds. These flows manifest dynamic meso-scale structures that span a wide range of spatial and temporal scales. These structures can be resolved by CFD-DEM simulations in small computational domains. However, the computational cost to resolve them in simulations of flows in large industrial units is prohibitive, where coarse-grained simulation approaches such as CFD-DPM (discrete parcel method) and MP-PIC (multi-phase particle-in-cell) are more viable [1,2,3]. In these coarse-grained simulations, only a small number of representative particles (a.k.a. “parcels”) are simulated and particle-particle interaction is treated via tracking collisions between particles [4] or a physically reasonable particle phase stress model [2,3]. In previous studies of our group [5,6], we proposed the coarse-grained fluid-particle drag relation for coarse CFD-DEM/DPM and MP-PIC simulations of industrial scale gas-particle flows. The goal of the present study is to provide the particle stress model for coarse MP-PIC simulations. We first performed highly resolved CFD-DEM simulations of gas-fluidization of mono-disperse particles in periodic domains at various solid volume fractions. By following the particle coarsening methodology given by [6], the results are analyzed to formulate an effective particle phase stress model. This model is then assessed in a posteriori manner through crossing jets and Taylor-Green vortex flow test cases.