The boundary layer measurements of Klebanoff

The boundary layer measurements of Klebanoff (1955) are shown in Figure 8.3.

Figure 8.3

Two features are worth noting:

• All turbulent quantities go to zero at the edge of boundary layer.
• Turbulence intensity normal to the wall is smallest and is highest in the main flow direction.

On the scales in the figure we do not see the variation close to the wall. In fact all turbulent quantities should vanish at the wall. This is illustrated in the inset diagram where the intensity in the streamwise direction is measured close to 0.002 of the boundary layer thickness

Important Remarks: The fluctuations are an inherent component of the turbulent flow. The fluctuations are functions of time, they do not grow or decay with time.