The effects of seven geometrical parameters on the cyclone separator performance and the flow field are investigated via eight mathematical models and computational fluid  dynamics (CFD) Fluent software. A cyclone separator with tangential inlet was used to estimate the effect of geometrical parameters on the pressure drop and cut-off size (collection efficiency). A prediction model of the pressure drop and cut-off diameter was obtained based on response surface methodology by means of the statistical software. The results show that the vortex finder diameter, the inlet height, the inlet width, and the total cyclone height play an important role in influencing the cyclone performance other than other factors mentioned in publications. The eight mathematical models used in this study, nearly all gave the same
conclusion. For more understanding of the effect of the geometrical parameters on the flow field of cyclone separator, Large Eddy Simulation investigations are performed for six test cases.