During phases i & ii, user-friendly computer software will be developed to be used by the Navy for computational modeling of three dimensional, unsteady, separated, recirculated, turbulent flows in marine gas turbine exhaust diffusers. The computational fluid dynamics (CFD) approach is based on a unique combination of the pressure gradient method and the mass-accelerated convergence scheme. The software is capable of predicting pressure drop, flow distributions, and thermodynamic losses, and may be applied to various configurations and the operational conditions of different designs. The final product will be an integrated package of numerical computation, geometric plots, grid generation, and graphic display. The primary objective of Phase I will be to build the technical foundation of the final product, including turbulence modeling, implementation of the mass-accelerated convergence scheme, modeling of steady and unsteady flows in components, and development of a grid generation scheme.