Mass transfer in turbulent flow

The local mass transfer coefficient in turbulent duct flow was measured using a new experimental technique. The experimental results agreed quite well with a numerical solution to the turbulent diffusion equation in channel flow. Formulation of the diffusion equation provided a continuous solution from a point near the discontinuity in mass flux to the fully developed region. The Nusselt numbers obtained numerically agreed with Spalding's asymptotic solution at longitudinal-distance to hydraulic-diameter ratios less than 0.02 and Hatton et al.'s eigenvalue solution for symmetrical heat transfer which is valid for longitudinal-distance to hydraulic-diameter ratios greater than 1. Current asymmetric heat transfer results in the fully developed region fell between the eigenvalue and numerical solutions.