HIGHER-ORDER DIFFERENTIAL-EQUATIONS OF RADIATIVE-TRANSFER - P3 APPROXIMATION

The boundary conditions to be used in the P3 approximation of the spherical harmonics method of the radiative transfer are formulated. The series expansion of the angular distribution of radiative intensity needed by the boundary conditions is extended to include the number of terms in the P3 approximation. This expansion is given for three-dimensional radiative transfer and the coefficients are determined in terms of the moments of radiation intensity. Although in this whole procedure tedious algebra is required, the final equations of the greatest importance are very convenient to use. The governing differential equations and the obtained boundary conditions for the P3 approximation are used to solve the radiation exchange for the case of the participating medium between plane parallel plates, concentric cylinders, and concentric spheres. © 1979 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.