Influence of one porous layer insert on the transient heat transfer in a tall annulus in presence of large source terms

This paper provides a sensitivity analysis on the influence of one porous layer insert on the transient behavior of natural convection in a tall annular enclosure in presence of large source terms. The porous medium which partially fills the cavity is characterized by a low value of the Darcy number, typical of insulating materials and metallic foams, often employed in heat exchangers and other engineering applications. A stabilized, fully explicit version of the Compressibility Based Scheme is here employed and validated against experimental data available in the scientific literature for steady and unsteady convection in vertical cylindrical enclosures. Several analyses are presented here by changing both the geometrical features of the cavity and the properties of the porous domain. The results of these analyses demonstrate that not only the thermo-physical properties of the porous medium but also the position and the thickness of the porous layer strongly affect the transient behavior of the convective phenomena occurring in the cavity.