Geng, J. T., Yujie; Wang, Wei. "Exploring a Unified EMMS Drag Model for Gas-Solid Fluidization," Chemical Engineering Science, 2022, p. 117444.
Abstract: Gas-solid fluidization is characterized by pervasive, dilute-dense two-phase flow structures, which need mesoscale drag modeling to account for their subgrid effects. The classic formulation of the energy-minimization multi-scale (EMMS) drag modeling requires a semi-empirical correlation of cluster diameter. To avoid using such a phenomenological description of mesoscale structures, in this work, we propose a two-level averaging approach: First, the mean drag in a fine-grid cell is defined as a weighted sum of the drag force in both the dilute and dense phases; Then, the second-level averaging is performed at the coarse-grid scale, where the unified EMMS drag is defined, and determined by performing a series expansion with respect to the phase-mean points of both the dilute and dense phases, respectively. The unified EMMS drag is validated with comparison to fine-grid simulation in a periodic domain and coarse-grid simulation of realistic fluidized beds, both showing fair agreement.
Keywords: mesoscale; fluidization; drag; EMMS; CFD simulation