THE operation of an engine test cell at low bypass ratios tends to amplify many adverse flow effects. This synoptic presents the results of a technique for test cell analysis called the combination technique which is a derivative of a threedimensional panel methods code. The results are compared to experimental data and when coupled with experimental data show that flow separation from the test-cell walls occurs at all cell bypass ratios. The results also indicate a relationship between this wall flow separation and vortex formation and ingestion. This technique represents a simple method to obtain an accurate aerodynamic analysis of a complex threedimensional flowfield in an engine test cell. Nomenclature Cp = pressure coefficient based on front cell pressure DF - fan diameter KBF = bypass flow velocity at highlight j/FC = front cell velocity X = station XUL = highlight station is composed of the test-cell walls, the engine with a bellmouth, and the engine thrust frame. The test-cell walls are square in cross section and impervious to the flow. The thrust frame is modeled by a solid enclosure. The bellmouth is modeled both internally and externally. To induce the engine flow, a nonzero normal velocity is imposed on the fan face. The core