SUMMARY
In this investigation, steady state two – dimensional laminar forced convection heat transfer of Newtonian and non-Newtonian fluids inside a duct of Rectangular shape has been studied numerically for a wide range of the Reynolds numbers of (Re.=.500 and 10000) with the Power law index (n) of Power law model ranging from (0.1 to 2), and Prandtl number of (Pr =1 and 10). Two types of boundary conditions have been considered. The first, when the side walls are heated with different uniform temperatures and the horizontal walls are insulated. The second, when the bottom wall is heated by applying a uniform heat flux while the other walls at the constant cold temperature. Also, the time independent non-Newtonian fluids under consideration were assumed obey to the Power law model. The numerical results of the values of average Nusselt number have been confirmed by comparing it to similar known previous works using the same boundary conditions. Good agreement was obtained. The results are presented in terms of isotherms and streamlines to show the behavior of the fluid flow and temperature. In addition, some graphs that repesent the relation between average Nusselt number and the parameters mentioned previously are drawn. Also, the results show that the power law index (n) has, for a given Reynolds and Prandtl numbers, a large effect on the heat transfer rate at high Reynolds number. Twelve different correlations to show the dependence of the average Nusselt number on the power law index, the Reynolds and Prandtl numbers has been fund.