P-N APPROXIMATION FOR RADIATIVE TRANSFER IN A NONGRAY PLANAR MEDIUM
Doctor of Philosophy
The P-N approximation is extended to treat nongray radiative transfer problems in planar media. The rectangular model is used to characterize the spectral dependence of the absorption coefficient. The P-1 and P-3 approximation formulations are presented. Solutions are obtained for the cases of radiative equilibrium, internal heat generation and combined conduction and radiation. The effects of the temperature dependence of the absorption coefficient are also investigated. The results show good comparison with the existing exact solutions. As would be expected, the P-3 approximation is superior to the P-1 approximation over the whole range of optical thickness.