Abstract: In this paper, the control volume method is used in the discretization process of governing equations about three-dimensional parabolic flows. The movement equations about cooling oil in radial grooves of wet multiple disc brakes are parabolic equations, so the velocity fields of cooling oil in grooves can be obtained when friction plate moves in various velocities. This provides theoretical basis for designing a wet brake and calculating heat trasfer coefficients between the friction plates and the oil flowing in the grooves.