As the need for missiles and rockets has increased exponentially, the challenges associated with the gas dynamics of these vehicles continues to be a concern. The pressure in the downstream is sub atmospheric whenever there is a sudden expansion. This low pressure in the recirculation zone causes significant drag, accounting for almost two-thirds of the net drag of the aerospace vehicles. Hence, the purpose of this paper is to deliver a Computational Fluid Dynamic (CFD) analysis of the impact geometry and flow parameters have on the thrust force generated by the flow from convergent divergent nozzles to a suddenly expanded circular duct with a wider cross-sectional area. By observing all of the results, it is possible to conclude that the flow field in an enlarged duct is greatly influenced by the area ratio.