Nonlinear iterative projection methods with multigrid in photon frequency for thermal radiative transfer

This paper presents nonlinear iterative methods for the fundamental thermal radiative transfer (TRT) model defined by time-dependent multifrequency (RT) equation and material energy balance (MEB) equation. The are based on projection approach use multiple grids in photon frequency. They formulated high-order RT a given grid frequency low-order moment equations hierarchy of grids. temperature is evaluated subspace lowest dimensionality from MEB coupled to effective grey equations. algorithms apply various multigrid cycles visit Numerical results presented demonstrate convergence TRT problems with large number groups.