抄録
Measurement of the velocity of a drag-reducing surfactant solution flow was carried out with the use of particle tracer velocimetry (PTV) to provide a better understanding of the mechanism of the drag reduction effect. From the results of the velocity data analysis, Reynolds stress is shown to be zero, but the turbulent intensity of the flow is still significant. The correlation between the two velocities at the pipe center and near the wall suggests that the flow of the drag-reducing surfactant solution is not a turbulent flow but some kind of a transitional flow. Such a transitional flow might include an intermittent laminar flow, which causes the Reynolds stress deficit.
