Temperature fluctuation appearing in bilayered thermal boundary in drag-reducing surfactant solution flow

Surfactant solution flow is known for the dramatic reduction in turbulent frictional drag, correspondingly, heat transfer coefficient varies complicatedly. It is interesting to investigate the effect of surfactant on the turbulent heat transfer mechanism. In the present study, we measured the mean value and fluctuation value of temperature and velocity using TC-probe and LDV and performed analysis. Because turbulence transfer changes by the addition of surfactant, the development of the thermal boundary layer is inhibited, and then the specific mean temperature distribution and temperature fluctuation intensity change appear. It is found that the turbulence transfer has the same actions for momentum and heat except the effect of the viscoelastic stress.