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

The hydrodynamics of gas-particle two-phase flow in a spouted fluidized bed was numerically investigated using the Eulerian-Eulerian two-fluid model. Considering the influence of wall boundary conditions on the flow pattern, this study focuses on the effect of the specularity coefficient. The specularity coefficient represents the degree of tangential momentum transfer when particles collide with the wall, and its value depends on the properties of both particles and the bed wall. The simulations were carried out in two dimensional based on the kinetic theory of granular flow for the solid phase, and the results were compared with available experimental and numerical data. Different values of the specularity coefficient (۰.۰۰۵, ۰.۰۱, ۰.۰۵, and ۰.۵) were examined to analyze their effect on the instantaneous and time-averaged solid volume fraction, vertical particle flux, vertical velocity, and air volume fraction at different bed heights. Increasing the specularity coefficient enhances the friction between particles and the wall, leading to a reduction in both the solid volume fraction and particle velocity near the wall. According to the results, specularity coefficients of ۰.۰۵ and ۰.۵ show the best agreement with the experimental data.

Keywords:

spouted fluidized bed , specularity coefficient , gas-particle flow , Eulerian-Eulerian model