Modifying the inter‐phase drag via solid volume fraction gradient for CFD simulation of fast fluidized beds

The conventional drag model in two‐fluid simulation, which assumes uniform particle distribution in a computational grid, overestimates the drag force, thus failed in capturing the subgrid‐scale strands and resolvable‐scale clusters. This work proposed a new modification to the conventional drag mod...

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Bibliographic Details
Published inAIChE journal Vol. 63; no. 7; pp. 2588 - 2598
Main Authors Su, Mingze, Zhao, Haibo
Format Journal Article
LanguageEnglish
Published New York American Institute of Chemical Engineers 01.07.2017
Subjects
CFD simulation
cluster
Clusters
Computational fluid dynamics
Computer applications
Computer simulation
Drag
drag coefficient
fast fluidization
Fluctuations
Fluid dynamics
Fluid flow
Fluidized beds
Flux
Mathematical models
Reynolds number
Simulation
Strands
Stress concentration
Two dimensional models
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Summary:The conventional drag model in two‐fluid simulation, which assumes uniform particle distribution in a computational grid, overestimates the drag force, thus failed in capturing the subgrid‐scale strands and resolvable‐scale clusters. This work proposed a new modification to the conventional drag model through considering the heterogeneous distribution of solid volume fraction (SVF), especially, in the inter‐phase boundary (i.e., cluster boundary). The resulting drag model is a function of particle Reynolds number, SVF and the gradient of SVF. This straightforward modification is consistent with the elaborately filtered‐approach‐based modification method in nature. A CFD simulation for a two‐dimensional riser was conducted to validate the new drag model. The outlet solid mass flux, axial and radial time‐averaged voidages from the new drag model agreed well with the experimental measurements, and these results were far better than those from the conventional homogeneous drag models. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2588–2598, 2017
ISSN:0001-1541
1547-5905
DOI:10.1002/aic.15573