Title: Multi-model preconditioning for radiative transfer in high density regimes


			      Guido Kanschat
                    Institut f. Angewandte Mathematik
                          Universitaet Heidelberg
                                INF 293/294
                         69120 Heidelberg, Germany
                         Email: kanschat@dgfem.org
            Web page: http://gaia.iwr.uni-heidelberg.de/~kanschat/



Abstract:
Solution of the discrete systems arising from radiative transfer problems
is particularly demanding due to their size. Furthermore, in the case of
dense matter with a high albedo, the matrix is extremely badly conditioned. 
We show how the so called Eddington approximation of radiative transfer can 
be used to speed up the solution process considerably. The transfer of data 
between the original radiative transfer problem and the approximate model is 
facilitated using compatible discontinuous Galerkin discretizations for both. 
We show computational results exhibiting the feasibility of the method for 
higher order elements and a wide range of absorption and scattering 
coefficients.