Impact of aspect ratio on a nanofluid-saturated porous enclosure

The aim of the present numerical simulation is to investigate the mixed convection flow and heat transfer characteristics in a two dimensional porous cavity filled with nanofluid for different aspect ratios. The top and bottom walls are assumed to have the uniform temperatures theta(h) and theta(c), respectively, with theta(h) > theta(c) while the vertical walls are kept to be adiabatic. The governing equations are solved by using finite volume method with the SIMPLE algorithm. The variations of isotherms, streamlines, mid-plane velocity profiles, and Nusselt numbers were discussed in detail over a wide range of pertinent parameters, viz., aspect ratio, Richardson number, Darcy number, and solid volume fraction. Although the addition of nanoparticles in the porous medium is to increase the overall heat transfer rate in most flow regimes, the overall heat transfer rate is appeared to decrease slightly or stay nearly the same with the increase of solid volume fraction for Ar = 0.25 and 0.5 porous cavities in the forced convection regime.