Numerical study of natural convection taking into account radiation of absorbing gases

In this paper, the coupling between gray radiation heat transfer and natural convection heat transfer is studied. The governing equations of natural convection and the radiative transfer equation are solved simultaneously to obtain the temperature, velocity and heat flux distributions inside the participating media. The finite volume method has been adopted to solve the governing equations and the discrete ordinates method (DOM) is used to model the radiative transfer in an absorbingemitting medium. The radiative-convective model is validated by comparison with test cases solutions from the literature. Then, this model is applied to study the combined radiation-natural convection in a square cavity. The effects of optical thickness and wall emissivity on temperature and velocity distributions and Nusselt number are analyzed. The results show that even with a low temperature difference, the radiation plays a significant role on thermal and flow behaviors in the cavity.

Keywords:

radiation , natural convection , square cavity , discrete ordinates method