Natural Convection From L-Shaped Corners With Adiabatic and Cold Isothermal Horizontal Walls

Abstract

A numerical study of two-dimensional fluid flow and heat transfer by natural convection from L-shaped corners is reported. The vertical side is hot isothermal, and the horizontal side is either adiabatic or cold isothermal at the ambient temperature. The effect of changing the aspect ratio (length of the horizontal side/height of the vertical side) on the transport from the vertical side is studied in detail. It is shown that when the length of the horizontal wall is of the order of the boundary layer thickness on the vertical side, the entrainment flow as well as the boundary layer flow are influenced significantly by a change in the length of the horizontal surface. The heat transfer rate from the vertical side also decreases with increasing length. For values of the aspect ratio > 0.3 (Pr = 0.7), the Nusselt number for the vertical side of the L-shaped body is about 10 percent less than that for the vertical plate. As the length of the horizontal plate increases further, the flow in the outer region undergoes a significant change, but the heat transfer from the vertical heated leg remains unaffected. As the aspect ratio approaches = 2.0, increasing the length of the horizontal side ceases to have any further influence on the entire flow field. Comparison of Nusselt number with past experimental data for air shows good agreement. Finally, Nusselt number correlations in the range of Rayleigh number from 105 to 109 are presented.