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Mathematical Problems in Engineering
Volume 2015 (2015), Article ID 586913, 17 pages
Research Article

Comparative Study of Radiative Effects on Double Diffusive Convection in Nongray Air-CO2 Mixtures in Cooperating and Opposing Flow

1Faculty of Hydrocarbon and Chemistry, M’Hamed Bougara University, 35000 Boumerdes, Algeria
2Institut Pprime, CNRS, ENSMA, University of Poitiers, Futuroscope, 86961 Chasseneuil, France

Received 10 September 2014; Revised 27 January 2015; Accepted 28 January 2015

Academic Editor: Pedro Jorge Martins Coelho

Copyright © 2015 Siham Laouar-Meftah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study analyses the effects of nongray gas radiation on double diffusive convection, in a square differentially heated cavity filled with air-CO2 mixtures, when the buoyancy forces (thermal and mass) are cooperating or opposing. The radiative source term in the energy equation is evaluated by the discrete ordinate method (solving the radiative transfer equation) and the SLW spectral model (accounting for real radiative properties of absorbing species). Here, gas absorption varies with the local temperature and concentration of pollutant, which induces a strong direct coupling between the concentration and thermal fields that would not exist with gray gas. Simulations are performed at different concentrations of CO2 corresponding to different flow regimes (thermal, transitional, and mass). Results show the following: (i) in cooperating flow, radiation modifies essentially the heat transfer and the characteristics of temperature and concentration fields; (ii) in opposing flow, radiation effects are more important and depend on the nature of the flow regime.