Effect of surface radiation on buoyant convection in vertical triangular cavities with variable aperture angles

Abstract

The present investigation deals with the numerical computation of laminar natural convection with and without surface-to-surface radiation in a class of right-angled triangular cavities filled with air. The vertical walls are uniformly heated and the inclined walls are uniformly cooled while the upper connecting walls are adiabatic. The aperture angle φ located at the lower vertex of the triangular cavities between the vertical and the inclined walls identifies the shape of each cavity. This kind of cavity finds application in the miniaturization of cabinets housing electronic components constrained by space and/or weight severely. With a view at enhancing the heat transfer rates and/or reducing the size of cabinets, the influence that surface radiation exerts upon natural convection should be scrutinized. To this end, the finite volume method is implemented to perform the computational analysis of the above-described problem(s). Numerical results are reported for the local quantities, the velocity and temperature fields encompassing aperture angles φ that extend from 15° to 45° at two extreme Rayleigh numbers, Ra = 10 3 and 10 6. Additionally, the two global quantities, the mean convective Nusselt number and the mean radiative Nusselt number are reported in tabulated and graphical forms for the same controlling parameters. Overall, it was found that the competition between surface radiation and natural convection in right-angled triangular cavities filled with air plays a preponderant role. Finally, the analysis culminates with the construction of a comprehensive correlation equation for the total Nusselt number in terms of the controlling parameters which should be useful for engineering analysis and design. This correlation equation will undoubtedly provide a fast evaluation avenue to judge the cavity thermal performance.