Abstract: A two-level iterative method is proposed for linear systems discretizated from two-dimensional(2-D) radiative diffusion equations with photon, electron,ion temperatures(3-T).The main idea is to decouple one temperature from other two by a special coarsening strategy.Variables related to electron temperature are forced to be selected as coarse points and photon and ion temperatures are forced to be fine points.Several single temperature equations instead of coupled linear systems need to be solved by a classical-AMG method.The method is applied to the JFNK framework for preconditioning.Numerical results show effectiveness of the method.

Key words: two-dimensional three-temperature equations, radiation diffusion, algebraic multigrid (AMG), preconditioner, Newton-Krylov (NK)