Non-Newtonian Shear Thinning Effect on Natural Convection Flow over an Isothermal Elliptical Cylinder

摘要

In this paper, laminar natural convection flow of Newtonian and non-Newtonian (shear thinning case only) fluid surround an isothermal horizontal cylinder of elliptic cross section has been studied numerically. To characterize the non-Newtonian fluid, a modified power-law viscosity model has been employed. The boundary layer equations governing the flow are transformed into a non-dimensional form and the resulting equations are reduced to a convenient form which are solved numerically by an efficient implicit finite difference method. Numerical results are presented for two significant physical quantity such as the local skin friction coefficients and the rate of surface heat transfer (i.e. the local Nusselt number) as a function of the eccentric angle of an elliptical configurations with different aspect ratio and for different orientation such as blunt and slender. The local skin friction is found to be higher for Newtonian fluid than that of the shear thinning fluid. Furthermore, the total heat transfer rate becomes higher for elliptical cylinder with slender orientation than that of the blunt orientation in the fluids of interest.