Non-Newtonian viscosity, viscoelasticity, extensional viscosity and vortex inhibition were discussed as the anomalous phenomena of surfactant solutions. These phenomena appear to occur due to the aligned aggregate structure of threadlike micelles. The existence of the aggregate structure was indirectly confirmed from the rising behavior of a micro bubble in the pipe where the drag reduction occurs. We found out the relationship between the viscoelasticity and the maximum critical Reynolds number at which surfactant solutions lose their drag reducing ability. The vortex inhibition was shown to occur due to high viscosity for the twisting shear in the vortex stretching flow and its influence on the turbulent vortex structure was discussed.
