Numerical investigation of natural-convection heat transfer characteristics of Al<inf>2</inf>O<inf>3</inf>-water nanofluid flow through porous media embedded in a square cavity

In this study, natural-convection heat transfer characteristics of Al2O3-water nanofluid flow through a homogeneous porous medium embedded in a square cavity with several pairs of heaters and coolers located inside are investigated numerically. The two-dimensional equations governing the nanofluid flow and heat transfer through the porous medium are discretized using Streamline Upwind Petrov-Galerkin (SUPG) based Finite Element Method (FEM). The generalized Darcy-Brinkman-Forchheimer's porous medium model is used in this analysis. The average Nusselt number in the cases of the base fluid without a porous medium, of a nanofluid without a porous medium, and a nanofluid with a porous medium are compared for different Rayleigh numbers. It is found that in the case of the nanofluid with a porous medium the highest value of average Nusselt number was obtained. In addition to this, the effect of the Darcy number and the porosity on the pattern of streamlines and isotherms is investigated. It is also observed that the average Nusselt number increases with increasing Darcy number and decreases with increasing porosity and nanoparticle volume fraction.