PIV-PLIF Experiment on Modification of Turbulent Scalar Diffusion Near the Wall by Uniform Blowing

The transfer phenomena of wall turbulence are associated with the quasi ordered vortex structures, which are developed from small scale vortices near the wall. How to change the turbulent motion and turbulent transfer by modifying the condition of near wall is important for academic and industrial applications in the control of mass and heat transfers. In this study, we examined experimentally the effect on changing mass transfer in channel turbulence by uniform blowing from a porous wall. We used PIV/PLIF simultaneous measurement by mixing fluorescent dye into blown fluids to observe the spatial evolution of mass transfer in turbulence and analyzed flow fields from the view point of turbulence statistics. It was found that blowing enhanced fluctuation of disturbance and along with it, the coefficients of skin friction and mass transfer rate were increased. On the other hand, the isotropy of turbulence and turbulent Schmidt number were almost not changed. We concluded that there are universality in redistribution of turbulence energy and similar relationship between momentum and mass transfer.