Abstract
The present study is the experimental investigation of flow structures in the modified surfactant channel flow by simultaneous PIV and PLIF. In order to modify the near-wall region in the surfactant drag-reduced flow, water is dosed into the surfactant drag-reduced channel flow from a whole surface of the channel. By water dosing, drag reduction rate is enhanced compared to that without water dosing. The results show that the reason for this enhancement is the large decrement in the viscoelastic stress in the near-wall region while the slight increment Reynolds shear stress. In terms of velocity and concentration field, the feature in the near-wall region is similar to that in a usual Newtonian turbulence, however, the feature in the region remote from the wall is similar to that in a usual viscoelastic channel flow.
