Abstract
Surfactant solution for drag-reducing has non-Newtonian property with is shear-thinning viscosity. In this study, secondary flow of the surfactant solution in a 90° square bend is investigated by using PIV. The flow in bulk velocity V_b = 2.0m/s has the drag-reducing rate of 26% in the bend: The radial velocity component, V_y, is integrated over a given volume in order to estimate the magnitude of secondary flow. It is shown that the V_y component of secondary flow in the surfactant solution is greater upstream in the bend than that in water, and smaller downstream. In the whole region of the bend, the magnitude in the surfactant solution is smaller than that in water.
