Drag Reduction in a Small-Scale Circulation System of Surfactant Solutions

Turbulent drag reduction due to surfactant solutions was investigated for a small-scale pipeline system composed complex elements. The effects of the counter-ion concentration were discussed on the drag reduction, the viscoelastic characteristics, and the vortex inhibition. When the molar concentration of the counter-ion was ten times higher than that of the surfactant, the drag reduction appeared over the wide range of the surfactant concentration. This combination of counter-ion and surfactant exhibited a modest increase in viscosity, and the vortex inhibition appeared at a high stretching rate.