Abstract
It is known that surfactant additives in wall-bounded turbulent flows yielded the significant drag reduction. In this study, we performed flow visualization and LDV measurement of turbulent boundary layer using new experimental apparatus, in which the size is enlarged compared to old one, in order to clarify the drag-reducing effect at the higher Reynolds number. The nonionic surfactant which mainly consists of ODMAO is injected into the turbulent boundary layer. We could obtain the high drag redution up to 70%.
