Dispersion in Laminiar Flow of Non-Newtonian Fluids

In the present investigation, Taylor\u27s analysis of the dispersion of solutes in laminar flow of a Newtonian fluid through a circular tube was extended to the case of a non-Newtonian Eyring model fluid. A new approach was taken to solve the convective diffusion equation for the Eyring model fluid. This approach incorporates the use of the dimensionless longitudinal pressure gradient and the mean velocity to obtain the dimensionless concentration. Using an approach similar to that of Taylor, a solution of the diffusion equation was obtained for quantities such as the dimensionless concentration, mean concentration, and effective dispersion coefficient as a function of a dimensionless parameter describing the fluid. Experiments were conducted with fluids possessing non-Newtonian characteristics to obtain rheological and dispersion data. Two aqueous solutions, 0.1% and 1.0% Polyox (polyethylene oxide) were tested for rheological properties. These solutions were found to exhibit time independent non-Newtonian pseudoplastic fluid characteristics and fit the Ostwald-de Waele (Power Law) model quite well over the wide range of shear rate investigated