Numerical Simulation of Natural Convection in Three-dimensional Cavities with a High Vertical Aspect Ratio and a Low Horizontal Aspect Ratio

Abstract

In this article a commercial computational fluid dynamic program is used to study the effect of the horizontal aspect ratio on heat flow through cavities with a high vertical aspect ratio (cavities typically found in vertical window frames with internal cavities). The cavities studied have two opposite isothermal vertical walls separated by four adiabatic walls. The vertical aspect ratios are 20, 40, and 80 and the horizontal aspect ratios range from 0.2 to 5. Simulations of two-dimensional cavities are also included. The simulations show that three-dimensional cavities with a horizontal aspect ratio larger than five can be considered as being two-dimensional cavities to within 4% when considering heat transfer rates. Nusselt number correlations for the different horizontal aspect ratios are included. Complex multicellular flow is presented for one of the three-dimensional cavities.