Fluid and Particle Coarsening of Drag Force for Discrete-Parcel Approach

Fine-grid Euler-Lagrange simulations of gas-fluidization of uniformly sized particles have been performed in three-dimensional periodic domains. Snapshots obtained from these simulations have been systematically coarse-grained to extract filter size dependent corrections to the drag law that should be employed in coarse Euler-Euler (EE) simulations. Correction to the drag law that should be employed in Coarse Multi-Phase Particle-in-Cell (MP-PIC) model simulations is examined through a two-step process: separating the coarsening of the fluid and particle phases. It is found that the drag correction is almost entirely due to the coarsening of the fluid cells, with particle coarsening having only a weak effect. It is shown that drag correction for coarse EE and MP-PIC simulations are comparable. As a result, coarse drag models developed for EE simulations can serve as a good estimate for corrections in MP-PIC simulations, and vice versa.