A new approach to solve the radiative transfer equation in plane-parallel semitransparent media with variable refractive index based on the discrete transfer method

The radiative transfer equation in plane-parallel semitransparent media with variable refractive index is solved by the discrete transfer method. The medium refractive index is assumed to be constant in each control volume, such that the rays travel straight lines in control volumes, and redirect at interfaces. The effects of medium's refractive index on the curvature of solid angles are considered by a new set of weights, which are dependent on both ray path and medium's refractive index. The results are verified by comparing with a benchmark problem and the performance of the method is examined by various examples.