NUMERICAL-ANALYSIS OF THE THERMAL-CONVECTION FOR HERSCHEL-BULKLEY FLUIDS

This article presents a numerical analysis of the laminar forced conve ction in a cylindrical duct for a thermodependent Herschel-Bulkley flu id. Two boundary conditions are considered: constant wall heat flux an d constant wall temperature. Both fluid flow and heat transfer are stu died. The governing equations are solved using the finite difference m ethod with an implicit scheme. It is assumed that all fluid properties other than consistency K, are constant. The K-T relation used is K = K-0 exp (- bT). The results obtained enable us to characterize complet ely the dynamic and thermal fields structure. For a practical use of t he computed results, correlations for local Nusselt number and pressur e gradient are proposed taking into account the modification of the wa ll shear rate induced by the theological properties and the temperatur e-dependent character of the fluid.