A Hybrid Symbolic Monte-Carlo method for radiative transfer equations

We introduce a new model for radiative transfer equations where low energy groups are treated in the diffusion approximation whereas high energy groups are solution of the classical transport equation. This enables to extend the range of validity of usual Implicit Monte-Carlo techniques which behave poorly in regions characterized by a small mean free path. We show that Fleck's numerical scheme [J. Comput. Phys. 8 (1971) 313] is not adapted to this modeling and we present an application of Symbolic Monte-Carlo. Properties of the Monte-Carlo matrix are discussed and numerical results are presented. (C) 2003 Elsevier Science B.V. All rights reserved.