Transverse curvature effects in turbulent boundary layer

The effect of transverse surface curvature on the turbulent boundary layer is reviewed by recourse to experiments on axial flow along a circular cylin der. Three flow regimes are identified depending on values of the two contr olling parameters, namely, the Reynolds number and the ratio of the boundar y layer thickness to cylinder radius. The boundary layer flow resembles a w ake 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. Wh en the boundary layer is thick and the Reynolds number is small, which is t ypical of laboratory investigations, the effect of transverse curvature is felt throughout the boundary layer with evidence for relaminarization at th e low Reynolds numbers. This review describes the experimental evidence and points out gaps that remain. (C) 1999 Elsevier Science Ltd. All rights res erved.