Numerical calculation of radiative heat transfer in two-dimensional rectangular zone

The accuracy of the P1-approximation of the spherical harmonic’s method and the S2-approximation of the discrete ordinate method for calculating heat transfer by radiation are analyzed. The cases of an isotropically scattering homogeneous medium and a homogeneous absorbing medium are considered. The calculation results are compared with the exact solution, the P3-approximation and the zonal method. It is shown that the accuracy of the S2-approximation is higher compared to the P1-approximation at small and intermediate values of the optical thickness of the medium.