Near-wall investigation of three-dimensional turbulent boundary layers

he near-wall region of two three-dimensional turbulent boundary layers was investigated to observe the effect of cross-flow on statistical turbulence quantities and near-wall quasi-coherent structure. Three-dimensionality was produced using the following experimental configurations: (i) flow in a 30 degree bend and (ii) flow approaching a swept, 45 degree forward facing step. Measurements of mean velocities and turbulence quantities were obtained with a three component LDA system. Near-wall turbulence structure was investigated through the analysis of dye injection and hydrogen bubble wire flow visualization.;Mean flow data collapsed well on a law of the wall based on the resultant velocity, where the wall shear stress used in the non-dimensionalization was determined directly from the velocity gradient at the wall. Analysis of flow angles indicates non-collateral flow in the near-wall region since the flow angles changed throughout the viscous sublayer.;For both experimental configurations, the turbulence intensity and the magnitude of the turbulent shear stress increased with increased three-dimensionality. However, the ratio of these two turbulence quantities, the a;The shear stress vector lagged the velocity gradient vector in the outer regions of the boundary layer. Coincidence of these two vectors was observed near the region of maximum cross-flow, around y;Flow visualization using the dye injection technique showed that the average spanwise streak spacing in the near-wall region did not change from the observed two-dimensional value of 100 viscous units. From analysis of the hydrogen bubble wire flow visualization in the near-wall region...