View factor calculation in the 2-D geometries using the collapsed dimension method

Usage of the collapsed dimension method (CDM) applied so far in solving radiative transport problems with participating media has been extended for the determination of view factors of the 2-D geometries. Unlike its application in the participating media, in view factor calculations, the CDM does not require tracing of rays, and thus its expressions are exact. To test the applicability of the CDM for the calculation of view factors, two geometries were considered. The CDM results were found to match precisely with the exact results. If in the CDM, the view factor expressions are not considered exact, the ray tracing becomes mandatory and, in this method too like the discrete ordinate method, the discrete transfer method and the finite volume method, ray effect manifests. For this situation, for a given number of control surfaces, effects of number rays were studied and trends were found similar to those found in other methods.