Structure of Turbulence in the Boundary Layer near the Wall

Abstract

Previous measurements of space‐time correlations of turbulent wall pressure and velocity in the boundary layer were extended to include space‐time correlations between the wall pressure and all three velocity components in the vicinity of the wall. Additional measurements of space‐time correlations between various velocity components have also been made. The velocity correlations include measurements of the spatial correlation of the streamwise component of the fluctuating wall shear stress. A qualitative model is proposed for the structure of that portion of the turbulent field near the wall that is correlated with the wall pressure. The model outlines the sequence of events that result in the production of intense pressure and velocity fluctuations by stretching of the vorticity produced by viscous stresses in the sublayer. All the measurements show that the shape and size of the contours of constant correlation and the sign of the measured correlations are in agreement with the proposed model for turbulent structure.