Development of the WSGGM Using a Gray Gas Regrouping Technique for the Radiative Solution within a 3-D Enclosure Filled with Nonuniform Gas Mixtures(<Special Issue>Advanced Fluid Information)

A narrow band based WSGGM with a gray gas regrouping technique is proposed for nonhomogeneous and nonisothermal combustion gas mixtures. Applying the multiplication property of narrow band-average transmissivities for gas mixtures of CO_2-H_2O, the number of gray gases, required for accurate representation of the absorption characteristics by using the narrow band based WSGGM, is increased drastically. To reduce the computational loads by reducing the number of gray gases, we propose a gray gas regrouping process where the gray gases used for the WSGGM are regrouped into a specified number of groups according to the magnitudes of absorption coefficients. To evaluate the proposed WSGGM for gas mixtures, the radiative transfer problems through CO_2-H_2O gas mixtures in 1- and 3-dimensional enclosures are solved numerically by using the discrete ordinates method. The radiative heat source terms and the radiative heat fluxes obtained by using the proposed method are fairly well compared to those obtained by using the more accurate statistical narrow band model with an excellent computational efficiency.