Natural Convection Through an Open Cavity Heated From the Side and Filled With Fluid and Discrete Solid Blocks

In this study, natural convection inside a square open cavity containing several solid obstructions is modeled and numerically simulated. The horizontal surfaces of the cavity are adiabatic, while the vertical left wall is isothermally heated. The cavity, opened on the right side to a fluid reservoir, is filled with equally spaced, disconnected, square conducting blocks. The total amount of solid constituent within the enclosure is kept constant by fixing the cavity solid volume-ratio at 36% (equivalent to porosity equal to 64%). The effects of varying the number of solid blocks used and the Rayleigh number on the Nusselt number (based on the surface-averaged heat transfer coefficient along the heated wall of the enclosure) and on the volumetric flow rate entering the cavity induced by the natural convection are considered in detail. The results show the Nusselt number to be affected by the phenomenon of interference caused by the blocks, which increases in predominance as Ra increases. The volumetric flow rate, on the other hand, shows less of an effect by the interference of the blocks to the boundary layer, and more the flow hindrance effect of the blocks within the entire cavity. This effect is shown, nevertheless, to predominate when Ra is small — similarly to the interference effect.