Micellar Structure Break-Up and Recovery in Turbulent Flow of Drag-Reducing Surfactant Solutions

Abstract

Some surfactant solutions in turbulent flow exhibit up to 80% wall friction reduction compared to water flow. This drag reduction is believed to result from the interactions between flow turbulence and large structures formed of cylindrical micelles. These shear-induced structures (SIS) form when the micelles are exposed to shear generated by the flow field. When the shear stress in the flow exceeds a critical level, the drag reduction disappears (i. e. “mechanical degradation” takes place), but only temporarily so. If the stress is subsequently reduced below the critical level, the drag reduction reappears. In this work, we studied the phenomenon of mechanical degradation as a tool for temporary local elimination of the drag-reducing effectiveness of surfactant solutions. Our fundamental objective here was a better understanding of the degradation phenomena under various flow conditions, and their possible connection with the micellar kinetics and relaxation phenomena observed in still fluids.KeywordsSurfactant SolutionDrag ReductionMechanical DegradationCylindrical MicelleDegradation PhenomenonThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.