A computational analysis tool was used to characterize the flow structure in an S-shaped intake to determine the relationship between inlet shape and angle of incidence and to study the reduction of flow distortion on the engine face. A Royal Aircraft Establishment M 2129 S-shaped intake was used to establish the reliability of the proposed computational analysis technique. On the basis of previous research, the k-ω shear stress transport model for turbulence was used, and reliable results were obtained for complex flow structures, such as the secondary flow caused by adverse pressure gradient. The size of owl face separation and the angle of incidence at which the separation occurred differed according to the relation between the angle of incidence of the flow and the inlet shape. The size of the owl face separation was small in the S-shaped intake with an inlet shape close to that of an upper semicircle. Flow separation was delayed with respect to the angle of incidence.