Hybrid finite element and ray-tracing methods for radiation transport problems with voids

Dealing with low density regions is generally problematic for radiation transport methods based on the even-parity form of the transport equation. This paper is concerned with the linking of the Finite Element-Spherical Harmonics (FE-P-N) method, for solving the even-parity equation in high density regions and the ray-tracing (RT) method for low density regions. The resulting hybrid method proves to be both more accurate and more computationally efficient in certain problems, where unnecessary meshing can be avoided in the low density region.