AN EXPERIMENTAL STUDY OF THE STRUCTURE OF TURBULENCE NEAR THE WALL THROUGH CORRELATION MEASUREMENTS IN A THICK TURBULENT BOUNDARY LAYER.
MICHIGAN UNIV ANN ARBOR AERODYNAMICS LAB
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An experimental investigation is described in which emphasis is given to revealing the structure of turbulence near the wall in a boundary layer. Measurements made include space-time correlations between the fluctuating wall pressure and the span-wise velocity component w, and between the various velocity components. The velocity correlations include measurements of the space-time correlation of the streamwise component of the fluctuating wall shear stress. Experiments have been conducted in a thick 5 in. turbulent boundary layer with zero pressure gradient which is produced by natural transition on a smooth surface. Sufficient data have been obtained to allow the proposal of a qualitative model for the structure of turbulence near the wall. The proposed model outlines the sequence of events that results in the production of intense pressure and velocity fluctuations by stretching of the vorticity after it is produced by viscous stresses within and near the edge of the viscous sublayer. The measurements are in qualitative agreement with the model. Qualitative agreement means that the size and shape of the contours of constant correlation and the sign of the measured correlations are in agreement with the proposed model for the turbulent structure. Author
- Fluid Mechanics