Filtered sub-grid constitutive models for fluidized gas-particle flows constructed from 3-D simulations. (2nd October 2016) - Sarkar, Avik
Abstract: The accuracy of fluidized-bed CFD predictions using the two-fluid model can be improved significantly, even when using coarse grids, by replacing the microscopic kinetic-theory-based closures with coarse-grained constitutive models. These coarse-grained constitutive relationships, called filtered models, account for the unresolved gas-particle structures (clusters and bubbles) via sub-grid corrections. Following the previous 2-D approaches of Igci et al. [AIChE J., 54(6), 1431–1448, 2008] and Milioli et al. [AIChE J., 59(9), 3265–3275, 2013], new closures for the filtered inter-phase drag and stresses in the gas and particle phases are constructed from highly-resolved 3-D simulations of gas-particle flows. These new closure relations are then validated through the bubbling-fluidized-bed challenge problem presented by National Energy Technology Laboratory and Particulate Solids Research Inc. Graphical abstract: Highlights: New coarse-grained filtered models for gas-particle flows. Filtered corrections for fluid-particle drag and solid/gas-phase stresses. More accurate CFD fluidized-bed predictions afforded using coarse grids. Filtered models validated using NETL/PSRI challenge problem.