Non-local perturbation techniques in radiative transfer.

Perturbation techniques are presented for reducing the required computing time and enhancoing the accuracy of calculations of energy transfer in a radiating gas. The methods reduce the number of grid points by treating a simplified problem and assuming a more manageable redistribution. The effects of spurious sources and sinks are considered only after a zero-th order solution is obtained, with its inherent errors. The Feautrier, perturbed integral, and Scharmer perturbation methods are discussed, noting techniques for incorporating them into any current numerical scheme for solving the transfer equation. The main benefit is faster computations for coupled gas-dynamic and radiative transfer problems.