POMRANING-EDDINGTON APPROXIMATION FOR RADIATIVE-TRANSFER IN A SPHERICAL TURBID MEDIUM

The Pomraning-Eddington approximation is used to solve the radiative t ransfer problem for anisotropic scattering in a spherical homogeneous turbid medium with diffuse and specular reflecting boundaries. This ap proximation replaces the radiative transfer integrodifferential equati on by a second-order differential equation which has an analytical sol ution in terms of the modified Bessel function. Here, we calculate the partial heat flux at the boundary of anisotropic scattering on a homo geneous solid sphere. The calculations are carried out for spherical m edia of radii 0.1, 1.0 and 10 mfp and for scattering albedos between 0 .1 and 1.0. In addition, the calculations are given for media with tra nsparent, diffuse reflecting and diffuse and specular reflecting bound aries. Two different weight functions are used to verify the boundary conditions. Our results are compared with those given by the Galerkin technique and show greater accuracy for thick and highly scattering me dia.