Abstract
This paper provides a numerical simulation of a three-dimensional (3D) time-dependent nanofluid flow and heat transfer enhancement in 3D cubic enclosures using Buongiorno's non-homogeneous two-phase nanofluid model. The flow domain is filled by a homogeneous/heterogeneous porous medium and different cases based on the type of the medium are considered. These cases area homogeneous porous domain, a heterogeneous porous domain in all directions, a heterogeneous cavity with stratification in the X-Y plane, a heterogeneous cavity with stratification in the X-Z plane, and a heterogeneous cavity with stratification in the Y-Z plane. In the considered nanofluid model, types of the base fluid and nanoparticles can be determined; those are water and Al2O3, respectively, and impacts of the Brownian motion and thermophores parameters are significant. The results revealed that the optimal case of the heat transfer enhancement is the heterogeneous case in all directions (eta(1) = eta(2) = eta(3) = 1.5) while the homogeneous case has the lowest rate of the heat transfer. Also, the average Nusselt number is augmented as the Rayleigh-Darcy number (Ra-m = Ra x Da) is growing, regardless the properties of the porous medium. This numerical investigation is also germane to the reservoir rocks, fibrous insulation, and thermal insulation of buildings.