The Air Force has expressed interest in improving the efficiency of the Subsonic Aerodynamic Research Laboratory (SARL) wind tunnel. In a previous analysis of losses throughout the tunnel, it was found that approximately thirty percent of pressure losses through the tunnel occurred at the exit of the tunnel (Britcher, 2011). The use of alternative diffuser geometries in reducing pressure losses at the exit of the tunnel and the computation of their efficiency improvement with respect to the original tunnel geometry and with respect to each other for the SARL wind tunnel are the focus of this research. Three different diffuser geometries were evaluated numerically using both the SolidWorks Flow Simulation add-on, and ANSYS FLUENT. For each of these geometries, a scaled down model was manufactured to be used for experimental validation in future work. Both the full size and small scale numerical models were evaluated with an inlet velocity of sixty meters per second. As the nature of the flow at this point in the wind tunnel is not known, both a uniform and fully developed turbulent flow profiles were evaluated for each design, both for the small scale models and the full size models, to determine pressure losses with respect to the varying flow types entering the diffusers. This research seeks to determine the effects of these different geometries on the flow downstream of the exit, and the possible energy savings associated with each design. In addition, it seeks to compare the numerical results obtained from both SolidWorks Flow Simulation and ANSYS FLUENT.