NUMERICAL-SIMULATION OF DISPERSION IN THE FLOW OF POWER-LAW FLUIDS IN CURVED TUBES

Taylor's model is used as a framework to study axial dispersion in non-Newtonian power law fluids in a circular curved tube for low Dean number. A spectral model that calculates the solutions effectively for large values of Dn2Sc (where Dn is Dean number and Sc is Schmidt number) is chosen to obtain realistic results. The resulting algebraic equations are solved by Gauss elimination with partial pivoting. It is found that in the range of Dn2SC from 100 to 10(4) the axial dispersion in a circular curved tube is markedly less than that in a straight tube. At a large value of Dn2Sc. e.g., 5 x 10(4), the effective diffusion coefficient of power law fluids is reduced to a steady value, which is about 0.28 of their straight tube value. Our numerical results, in general, are found to be in good agreement with the experimental results for different curvature ratios and for small values of Dn2Sc (0(1)-0(10)). Between the range 0(10(2)) to 0(10(4)) of Dn2Sc, the agreement is excellent for higher values of curvature ratio.