High Schmidt number mass transfer using Chapman–Kuhnʹs near wall coherent structure model

High Schmidt number mass transfer in a fully developed turbulent flow is examined using a near wall coherent structure model. The computational approach relies on specification of idealized boundary conditions in the form of a two eddy structure imposed at a distance of y+=40 away from the wall. The parameters describing the spatial and temporal eddy behavior are obtained from a combination of experimental observation, analysis and computer trials as described by D.R. Chapman, G.D. Kuhn (AIAA Paper 81-1024 (1981) 306–316). Among these parameters, those describing the root mean square (rms) velocities in normal and spanwise directions are found to have significant influence on mass transfer at the wall. A correlation relating the mass transfer rate and the rms velocities is obtained. The effects of turbulence intensity on eddy viscosity and eddy diffusivity are also determined.