Transverse curvature effects in turbulent boundary layer

Abstract

The effect of transverse surface curvature on the turbulent boundary layer is reviewed by recourse to experiments on axial flow along a circular cylinder. Three flow regimes are identified depending on values of the two controlling parameters, namely, the Reynolds number and the ratio of the boundary layer thickness to cylinder radius. The boundary layer flow resembles a wake when both parameters are large. As expected, the effect of curvature is small when the Reynolds number is large and the boundary layer is thin. When the boundary layer is thick and the Reynolds number is small, which is typical of laboratory investigations, the effect of transverse curvature is felt throughout the boundary layer with evidence for relaminarization at the low Reynolds numbers. This review describes the experimental evidence and points out gaps that remain.