Improved steady-state diffusion approximation with an anisotropic point source and the delta-Eddington phase function

摘要

Using the algebra transformation method, we develop and demonstrate the use of the delta-P_(1) approximationto improve steady-state radiative-transfer estimates on spatial scales comparable to the mean free path. We show that the delta-P_(1) approximation agrees well with Monte Carlo simulation from source to infinity when we choose an appropriate parameter f (fractional portion that scatters directly forward) in the delta-Eddington phase function. We also provide the empirical formula to determine the parameter f.