Effects of mean flow three dimensionality on turbulent boundary-layer structure

Several experimental studies examining the near-wall structure of three-dimensional turbulent boundary layers are reviewed. The reduction of the Reynolds shear stress by the mean flow three dimensionality is a common feature of all of these flows. The near-wall region (y + < 100) is found to be dominated by quasistreamwise vortices and low- and high-speed streaks similar to two-dimensional boundary layers. However, the development of the vortices and their production of shear stress is modified by the presence of mean flow skewing across the near-wall zone. The implications of these findings are discussed.