Numerical solution and Taguchi experimental method for variable viscosity and non-Newtonian fluids effects on heat and mass transfer by natural convection in porous media

In this article, both numerical solution and Taguchi method are presented to study the variable viscosity and non-Newtonian fluids effects on coupled heat and mass transfer by free convection over a vertical permeable plate in porous media. The surface temperature, concentration of the plate, and blowing/suction velocity are uniform. The viscosity of the fluid varies inversely as a linear function of the temperature. The partial differential equations are transformed into non-similar equations and solved by Keller box method. Numerical results of the local Nusselt number and local Sherwood number are expressed in the five parameters: 1) blowing/suction parameter ξ; 2) the power-law index of non-Newtonian fluid n; 3) buoyancy ratio N; 4) Lewis number Le; 5) viscosity-variation parameter θr. The best value for confirming the maximum of the local Nusselt (Sherwood) number by the Taguchi method is 6.6328 (10.3056).