During the second half of the 90 s, NASA performed experimental investigations on six novel thrust reverser (TR) designs; core-mounted target-type thrust reverser (CMTTTR) design is one of them. To assess the CMTTTR efficiency and performance, NASA conducted several wind tunnel tests at sea level static (SLS) conditions. The results from these experiments are used in this paper series to validate the computational fluid dynamics (CFD) results. This paper is part one of the three-part series. Parts 1 and 2 discuss the CMTTTR in stowed and deployed configurations; all analyses in the first two papers are performed at SLS conditions. Part 3 discusses the CMTTTR in the forward flight condition. The key objectives of this paper are: first, to perform the three-dimensional (3D) CFD analysis of the reverser in stowed configuration; all analyses are performed at SLS condition. The second objective is to validate the acquired CFD results against the experimental data provided by NASA (Scott, C. A., 1995, “Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program,” NASA—Langley Research Centre, Hampton, VA, Report No. TM-2000-210300). The third objective is to verify the fan and overall engine net thrust values acquired from the aforementioned CFD analyses against those derived based on one-dimensional (1D) engine performance simulations. The fourth and final objective is to examine and discuss the overall flow physics associated with the CMTTTR under stowed configuration. To support the successful implementation of the overall investigation, full-scale 3D computer aided design (CAD) models are created, representing a fully integrated GE-90 engine, B777 wing, and pylon configuration. Overall, a good agreement is found between the CFD and test results; the difference between the two was less than 5%.