Flow with high Reynolds numbers around aircraft and space vehicles generates viscous layers. The viscous layers are thin as long as they are attached onto the configuration (wings, fuselages, aerodynamic controls, etc.). These flows are mainly governed by the velocity gradient perpendicular to the body contour and can be treatedPulliam, T.H. bySteger, J.L. theHÄnel, D. so-calledSchwane, R. ThinMolvik, G.A. LayerMerkle, C.L. Approximation (TLA), [1–3]. The TLA procedure is very similar to the boundary layer approach with the difference that no matching is necessary between inviscid flow solution (e.g. Euler solution) and the boundary layer solution. In contrast to the classical boundary layer theory, the momentum equation normal to the wall is maintained and is not replaced by \(\partial p / \partial n \approx \partial p / \partial z = 0 \) as in boundary layer theory, which means that the pressure must not be constant normal to the body surfaceNavier-Stokes equations thin layer (TLA).