The effects of curvature on the turbulent boundary layer

Abstract

Summary. Preliminary measurements in the turbulent boundary layers on a circular cylinder and the convex wall of a 90 degree curved duct are described. The results indicate quite significant effects of longitudinal surface curvature on the development of the boundary layer. In particular it is shown that (a) curvature has a marked influence on the velocity profiles, (b) the usual momentum integral equation for flat surface flow breaks down in the presence of large static-pressure variations across the boundary layer, and (c) none of the existing boundary-layer calculation methods adequately predicts the development of the shape factor. A more general momentum integral equation has been derived from first principles. This gives reasonable agreement with the experimental development of the momentum thickness.