Abstract: In this paper,the viscous flows in the two-dimensional vectored and unvectored nozzles are numerically simulated by three-dimensional time-dependent Navier-Stokes equations in conservation forms.Finite volume discretization is used in spatial form and Runge-Kutta method in time marching direction.A new viscous terms' discretization in the frame-work of the finite volume method is used which has the advantages of less operation counts and full conservation.A modified Baldwin-Lomax algebraic turbulent model and wall function law are also adopted in the prediction.Comparision of numerical predictions with experiments shows that the Navier-Stokes code can accurately predict the flow fields in the vectored and unvectored nozzle where the flow is predominantly two-dimensional at the designed nozzle pressure ratios or above.Discrepancies between predictions and experiment are found at lower nozzle pressure ratios where separation typically occurs in a large portion of the nozzle.