Modares Mechanical Engineering

Modares Mechanical Engineering

Numerical study of the effect of specularity coefficient in Eulerian–Eulerian simulation of spouted fluidized beds

Document Type : Original Article

Author
Hamed Khosravi-Bizhaem
Department of Mechanical Engineering, Faculty of Mechanical and Materials Enginering, Birjand University of Technology, Birjand, Iran
10.48311/mme.2026.118839.82944
Abstract
The hydrodynamics of gas–solid two-phase flow in a spouted fluidized bed was numerically investigated using the Eulerian–Eulerian model. In this study, the effect of the specularity coefficient, which represents the degree of tangential momentum transfer during particle–wall collisions, was examined. Two-dimensional simulations were carried out using the kinetic theory of granular flow for the solid phase, and the obtained results were compared with available experimental data as well as numerical results based on the Eulerian–Lagrangian approach. Different values of the specularity coefficient (0.005, 0.01, 0.05, and 0.5) were considered, and their effects on the hydrodynamics of gas–solid flow at different bed heights were analyzed. By comparing the present results with previous Eulerian–Lagrangian simulations, the maximum deviation in the time-averaged vertical particle mass flux was found to be 6.5% at the bed center and 18.1% near the wall. In addition, the differences in the time-averaged vertical air velocity at the bed center ranged from 5.7% to 20.4% at different heights. These discrepancies can be attributed to factors such as the drag correlation, solid restitution coefficients, and solid pressure and viscosity models, which were not examined in the present study. The results indicate that increasing the specularity coefficient enhances particle–wall friction, leading to a reduction in the solid volume fraction and solid velocity near the wall. Based on the obtained data, specularity coefficients of 0.05 and 0.5 show the best agreement with experimental measurements and Eulerian–Lagrangian model predictions.
Keywords
spouted fluidized bed؛ specularity coefficient؛ gas-solid flow؛ Eulerian&ndash
Eulerian

Subjects

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Modares Mechanical Engineering
Volume 26, Issue 5
April 2026
Pages 293-305