On Simplified Spherical Harmonics (SPN) and Generalized SPN (GSP(N)) formulations

Simplified P-N (SPN) equations are derived based on variational method using a modified version of ansatz originally proposed by Pomraning. New boundary and interface conditions are derived for the SPN equations using the corresponding angular flux expression. The equivalence of equations, thus derived, along with its interface and boundary conditions with those of a specific case of Generalized SPN (GSP(N)), put forward by Chao, is brought out. (C) 2022 Elsevier Ltd. All rights reserved.