Abstract：In order to reveal the fluidization characteristics of binary particles， the 3D computational fluid dynamics （CFD） simulation on the instantaneous segregation process of binary particles in gas -solid fluidized bed was performed using the multi-fluid model based on Eulerian-Eulerian method. The effects of the definition of residual， maximum packing limit，and specularity coefficient on the instantaneous segregation extent were investigated. The results demonstrate that the definition of residual changes the real iterations per time step，which has a significant influence on the predicted instantaneous segregation extent. The instantaneous segregation extent increases remarkably with the increase of maximum packing limit. The segregation behavior of binary particles is hindered for smaller specularity coefficient，which leads to a lower instantaneous segregation extent.

Keywords: computational fluid dynamics; binary particles; segregation; fluidized bed