Acute anisotropic scattering in a medium under collimated irradiation

This article deals with the assessment of the Finite Volume Method (FVM) to solve the radiative transfer equation (RTE) in 3D acute forward-scattering media with collimated irradiation. Phase functions of the Henyey-Greenstein (HG) type with asymmetry factors ranging from 0.2 to 0.93, and a Mie phase function with an asymmetry factor of 0.93, are considered. The test case involves a purely scattering medium in a cubic enclosure, with a collimated irradiation with zero incidence impinging on one face. FVM results are found to be consistent with reference solutions obtained by the Monte Carlo Method (MCM) whatever the magnitude of the forward peak and the optical thickness considered. The FVM appears to be a good candidate to treat such problems since it requires no modification of its classical formulation, resulting in a straightforward implementation.