Nusselt number correlations for laminar convection in three-dimensional air-filled cavities

Abstract

This article deals with laminar natural convection in three-dimensional air-filled enclosures. The cavities under investigation have two opposite isothermal vertical walls and four adiabatic walls. The vertical and horizontal aspect ratios are in the range 5–80 and 0.2–5, respectively. The Rayleigh numbers vary between 10³ and 10⁵. These values match cavities typically found in vertical hollow alveolar bricks. The effects of the geometry and the Rayleigh number on the convection are discussed. Comparisons between purely two-dimensional cases and the results obtained in 3D are presented and analyzed. Nusselt number correlations as a function of the two aspect ratios and Rayleigh number are proposed, offering an efficient tool for thermal engineers and scientists to evaluate convection heat transfer in real three-dimensional enclosures, which are common systems in building construction.