Velocity measurement in turbulent boundary layer of drag-reducing surfactant solution

The influence of a drag-reducing surfactant on a zero-pressure gradient turbulent boundary layer was investigated using a two-component laser-Doppler velocimetry system. It was discovered that the streamwise turbulence intensity has a maximum near the center of the boundary layer in addition to the near-wall maximum which appears in canonical wall-bounded turbulent flow. At the location of the additional maximum, the Reynolds shear stress has a slight maximum, the skewness factor of streamwise turbulent fluctuation is zero, and the flatness factor has a minimum. (c) 2005 American Institute of Physics.