Diffusion approximation and computation of the critical size
Claude Bardos, R. Santos, Rémi Sentis · Transactions of the American Mathematical Society · 1984
This paper is devoted to the mathematical definition of the extrapolation length which appears in the diffusion approximation. To obtain this result, we describe the spectral properties of the transport equation and we show how the diffusion approximation is related to the computation of the critical size. The paper also contains some simple numerical examples and some new results for the Milne problem.