Convecção natural e radiação em cavidade aberta preenchida com meio poroso heterogêneo

Abstract

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 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 a square cavity, with one wall heated and the other opened to an adjacent fluid reservoir, having one or four square conducting solid blocks inserted in it. The resulting natural convection flow is simulated numerically via the finite-volume method, with the SIMPLEC algorithm, and the radiation effects incorporated via the S2S model. The investigation then evolves into a nondimensional parametric study considering the effects of block dimension, number of blocks, surface emissivity and Rayleigh number into the convection heat transfer process. The cavity filling fluid (air) is assumed to have constant and uniform properties, and the fluid-to-solid conductivity ratio is set as unity. 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. The results are then used to build a practical correlation for predicting the total Nusselt number as a function of the parameters investigated.