Impact of Non-Newtonian Fluids' Rheological Behavior on DoubleDiffusive Natural Convection in an Inclined Square Porous Layer

Abstract

his paper presents a numerical study of double-diffusive convection in a square cavity with a porous layer filled with a non-Newtonian fluid and subjected to uniform Neumann heat and air flows applied to the active walls of the cavity, while the other walls are considered adiabatic and impermeable. We used the Carreau-Yasuda rheological model, which is adequate for many non-Newtonian fluids, and is used to characterize the behavior of the shear-tinning fluids. The finite difference method is used to obtainthe numerical solution of the general governing equations, for a thin shear-thinning fluid with Darcy model and Boussinesq approximation were employed to model the convective flow in the porous medium. The governing parameters of the problem are the rheological parameters of Carreau-Yasuda, namely (??, ??, ??and ??),the thermal Rayleigh number , ????,the Lewis number????, the buoyancy ratio ??, and inclination angel, ?. the effects of the mentioned governing parameters, flow intensity, apparent viscosity, and heat and mass transfer rates, were illustrated and discussed in terms of steamlines, isotherm, isoconcentration, apparent viscosity contours, stream function, apparent viscosity profiles, the average Nusselt number and the average Sherwood number. The results indicate a strong influence of the shear behavior of the non-Newtonian fluid on the heat and mass transfer by natural convection inside the enclosure. the flow structure evolves from conduction to convection as the buoyancy ratio increases. TheNusselt, ????,and Sherwood,???,numbers increase along the transition path. The average number of ???increases considerably with the improvement of the number of Lewis number but the average number of ????changes slightly. The thermal and mass transfer is favored for an angle of inclination of 45°