Mass transfer in turbulent pipe flow of viscoelastic fluids

The mass transfer entry length and maximum mass transfer reduction asymptote for drag-reducing viscoelastic fluids have been calculated analytically using the successive approximation technique. The eddy diffusivity of mass reported by Shulman et al. (1980) and Virk's (1970) velocity profile corresponding to the maximum mass transfer reduction in turbulent pipe flow were applied to the present analysis. The mass transfer entry length for these fluids was found to be 8-40 pipe diameters depending on the Reynolds number. The predicted mass transfer rates for these fluids are in good agreement with available empirical mass transfer results, which show approximately 56-75% reduction in the mass transfer rate compared to the Newtonian values at the same Reynolds and Schmidt numbers. A comparison of these mass transfer results with available heat transfer measurements leads to the conclusion that there is no simple direct relationship between heat and mass transfer for drag-reducing viscoelastic fluids.