On the interaction of a 2-dimensional transonic turbulent boundary layer with a localized 3-dimensional disturbance

If a weak normal shock wave impinges on a fully attached transonic turbulen t boundary layer, a three layer structure develops. In the outer defect reg ion the solution of the interaction problem may be described as an irrotati onal perturbation to the oncoming stream. Hence a potential phi can be intr oduced, which is governed by a generalized transonic small-disturbance equa tion. In the present study it is shown that, for a suitable scaled problem, the interaction of the incoming boundary layer with a small 9-dimensional obstacle can be described by an equation of similar type. Numerical studies are carried out focusing on the formation of the local supersonic region w ithin the defect region of the boundary layer.