A procedure for computing radiation in semitransparent media is presented.
A conservative cell-based finite-volume method is developed for unstructure
d meshes composed of arbitrary polyhedra. The angular domain is discretized
into a finite number of control angles over which radiant energy is conser
ved. At Fresnel interfaces, numerical procedures are developed to conservat
ively transfer radiant energy from one angular direction to another as a re
sult of reflection and refraction, while accounting for control angle overh
ang. Similar procedures are also employed at specular surfaces and symmetry
boundaries. The method is tested against analytical solutions and shown to
perform satisfactorily.