Asymptotic derivation of the simplified P[sub n] equations
E.W. Larsen, Jim E. Morel, J.M. McGhee · University of North Texas Digital Library (University of North Texas) · 1993
The diffusion and simplified P[sub N] equations are derived from the transport equation by means of an asymptotic expansion in which the diffusion equation is the leading order approximation and the simplified P[sub N] equations are higher-order approximations. In addition, the simplified P[sub N] equations are reformulated in a canonical'' form that greatly facilitates the formulation of boundary conditions and the implementation of the resulting problem in a conventional multigroup diffusion code. Numerical comparisons of S[sub N], diffusion, and simplified P[sub N] solutions show that the simplified P[sub N] solutions often contain most of the transport corrections for the diffusion approximation.