Surface mesh refinement with the Slice Balance Approach (SBA)

We introduce a surface mesh refinement technique for use with the Slice Balance Approach (SBA) and compare it with a conventional volume mesh refinement technique. We compare the techniques using simple test problems and compute results using two SBA spatial solution schemes: a diamond-difference-like scheme and a step characteristic scheme. Surface mesh refinement can be used for neutral particle transport applications with geometrically-complex arrangements of sources situated within optically-thin but dimensionally large volumes of air. An example is a room with tanks and pipes and other equipment arrangements that contain sources and where dose rates or fluxes on various surfaces are desired. We show, for problems with the large mean free paths characteristic of neutral particle transport in air, that the surface meshing technique can be more computationally efficient than traditional volume meshing.