Temperature Dependence of Drag Reduction with Surfactant

Abstract

Temperature dependence of drag reduction with surfactant solution is discussed. To clarify the range of the drag reduction, time scale ration of the additive to coherent fine scale eddy is introduced for the near wall turbulence. Since the time scale of the additive is considered to be constant under the conditions of constant additive concentration and temperature, the time scale of the coherent fine scale eddy can substitute the time scale ratio. The maximum drag reduction ratio has no temperature dependence for 500ppm and higher, while it decreases with the temperature for 100 ppm. For 500 ppm and higher, the upper limit of drag reduction depends on the concentration of the additive when the fluid temperature is 35℃ and above. Temperature dependence of the upper-limit-time-scale increases with the concentration of the additive. The time scale of the additive decrease with both fluid temperature and concentration of the additive.