Numerical Simulations of Natural Convection With Radiation in an Open Cavity Containing a Conducting and Centered Solid Body

Although of relevance to a variety of engineering applications, the study of natural convection within an open cavity containing a conducting solid body is rarely found in the literature. Moreover, previous studies have pointed out that radiation heat transfer rates are at least of the same order of the laminar natural convection rates in cavities, making the inclusion of radiation effects and important step toward obtaining more realistic and practical results. The present study considers then a square cavity, with one wall heated and the other opened to an adjacent fluid reservoir, having a square conducting solid block centered in it and accounting for natural convection and radiation effects. Notice, for a large block size, the geometric configuration of the resulting flow channel is similar to that of a fracture along a reservoir wall. The resulting natural convection flow is simulated numerically for performing a nondimensional parametric study seeking to unveil the effects of block dimension, surface emissivity and Rayleigh number into the heat transfer process. The cavity filling fluid is assumed to have constant and uniform properties, as is the solid block, and the fluid-to-solid conductivity ratio is set as unity in the present study. The screening (radiation) effect caused by the presence of the solid block is discussed, as well as the convective and radiative drop phenomena. The convection and radiation Nusselt numbers are evaluated and compared for each simulated case.