ON LAMINAR BOUNDARY LAYERS NEAR CORNERS

Abstract

It is shown that the principal features of the structure of a non-separating laminar boundary layer near a sharp corner, deflecting the exterior inviscid flow through a small angle α*, depends on the solution of the conventional boundary-layer equations but with novel boundary conditions. Further these conditions take on one of two forms depending only on whether the exterior flow is supersonic or subsonic and the effects of the boundary layer upstream of the corner and of the wall temperature are purely scaling. The complete solution of these fundamental problems requires a formidable amount of computing which is not available and so the only solutions presented are linearised studies valid when |α*| is sufficiently small. When α* < 0 and the corner is concave these studies are used to estimate the conditions for separation in the form |α*| = O(Re−¼) both for subsonic and supersonic flows, where Re is a representative Reynolds number of the flow and it is conjectured that separation will also occur for finite values of α* Re¼ when α* > 0 and the corner is convex. A formal extension to boundaries having large curvatures κ* = O(Re−¼) is also given.