A comparison of two stream approximation for the discrete ordinate method and the SOS method

The two-stream discrete ordinates method and the two-stream successive orders of scattering method are compared, and the key features of two methods are discussed. Based on the convergence characteristics of successive scattering, we use a semi-empirical model to improve the computing efficiency in the SOS method. Using the delta-M method, we investigate the effect of the two two-stream method for non-absorbing and absorbing case respectively. The 32-stream DISORT is used as the benchmark for assessments of the relative accuracy of the two methods investigated. With the comparisons for the accuracy of flux, the results of the two two-stream methods are almost the same in general and the absorbing media lead to larger errors of flux compared with that of the non-absorbing case.