A FAST MULTIGRID ALGORITHM FOR ISOTROPIC TRANSPORT PROBLEMS .2. WITH ABSORPTION

A multigrid method for solving the one-dimensional slab-geometry S-N e quations with isotropic scattering and absorption is presented. The ca se with no absorption was treated in part I of this paper [Manteuffel, McCormick, Morel, Oliveira, and Yang, SIAM J. Sci. Comput., 16 (1995) , pp. 601-635]. Relaxation is based on a two-cell inversion, which is very efficient because it takes advantage of the structure of the two- cell problem. For interpolation we use kinked linear elements. The kin k is based on the amount of absorption present. The restriction operat or is full weighting. Numerical results show this algorithm to be fast er than diffusion synthetic acceleration (DSA) in all regimes. This sc heme is also well suited for massively parallel computer architectures .