Three Dimensional Laminar Convection Flow of Radiating Gas over a Backward Facing Step in a Duct

In this study, three-dimensional simulations are presented for laminar forced convection flow of a radiating gas over a backward-facing step in rectangular duct. The fluid is treated as a gray, absorbing, emitting and scattering medium. The three-dimensional Cartesian coordinate system is used to solve the governing equations which are conservations of mass, momentum and energy. These equations are solved numerically using the CFD techniques to obtain the temperature and velocity fields. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, all of the convection, conduction and radiation terms are presented in the energy equation. For computation of radiative term in energy equation, the radiative transfer equation (RTE) is solved numerically by the discrete ordinates method (DOM) to find the divergence of radiative heat flux distribution inside the radiating medium. The numerical results are presented graphically and the effects of the radiation-conduction parameter, optical thickness and albedo coefficient on heat transfer behavior of the system are investigated. Comparison of numerical results with the available data published in open literature shows a good consistency.