The false scattering and ray effect in spherical harmonics method, including P₁ and P₃ approximation, is studied. Physical models of parallel and oblique laser incidence into two-dimensional gray media are constructed and the temperature profile within the medium is investigated to examine the false scattering. The ray effect is analyzed by the net radiative flux in the boundary. Simulation results show that both false scattering and ray effect exist in the spherical harmonics method, and the ray effect is mitigated higher in P₃ than that in P₁ approximation. In addition, the ray effect in the spherical harmonics approximation mitigates with increasing optical thickness within gray medium.

Pseudo-random number generator(PNG) is necessary in the computing works using Monte-Carlo method.The main error lies in the calculation of pseudo-random number to influence the accuracy of the calculation by the Monte-Carlo method.In this paper,a new more sufficient method through which one can hope a better outcome-the STTDMR (symmetry test in two dimension media radiation)is presented.The STTDMR is feasible under several of conditions to test unlimited the PNG.Good generators may be distinguished from bad ones more successfully in further level.The STTDMR is used to test not only properties of pseudo-random numbers but also the correctness of the probability models.In order to give a full view of the STTDMR,the STTDMR is applied to test several PNGs,and finally a PNG-ZH which is better than traditional PNG in many ways is obtained.

The finite-volume method for the radiative heat transfer is applied to linearly anisotropic plane-parallel scattering media.The results are compared with those obtained by the existing exact solutions,the radiation element method and the Monte Carlo method.It is shown that the results obtained by the finite-volume method are reliable.According to the analysis,the effect of the phase functions on the radiative heat transfer has some definite regularity.Furthermore,it is found that the ratio of the dimensionless heat flux in two two-dimension slabs with different scattering phase functions is a monotonous function of the optical thickness.It can be used as a benchmark to verify the results obtained with other methods.

A ray split-off and tracing approach is presented to analyze the apparent spectral reflecting performance of a semitransparent fluid layer with undulant surface.For parallel incidence and diffuse incidence of the spectral radiation,the regular ray tracing and the inverse ray tracing are separately employed to realize tracing the ray split-off process.With a clear and simple solving idea, the approach possesses a high calculating rate and small demands for the EMS memory,and is flexible for this kind of problems.The results of the calculating example show the following facts.For diffuse incidence of the spectral radiation,the undulant curve of the surface lowers the reflecting ability of the fluid layer.While for parallel incidence of the spectral radiation,two kinds of different influences on the reflecting ability may be caused by the undulant curve.