Abstract: The working theory of hydrocyclone was introduced, and the fluid field in the hydrocyclones with different overflow pipes in depth was simulated respectively by FLUENT.The distribution of the velocity and the concentration of dispersed phase of the fluid field within hydrocyclone was analyzed based on the numerical simulation, and the influence on the separation efficiency of hydrocyclone by the depth of overflow pipe was discussed.

Key words: Hydrocyclone, Overflow pipe, Separation efficiency