Infinitesimal-Area Radiative Analysis Using Parametric Surface Representation, Through NURBS

Abstract

The use of form factors in the treatment of radiant enclosures requires the radiosity be approximated as uniform over finite areas, and so when higher accuracy is required, an infinitesimal-area analysis should be applied. This paper describes a generic infinitesimal-area formulation suited in principle for any enclosure containing a transparent medium. The surfaces are first represented parametrically, through “non-uniform rational B-spline” (NURBS) functions, the industry standard in CAD-CAM codes. The kernel of the integral equation is obtained without user intervention, using NURBS algorithms, and then the integral equation is solved numerically. The resulting general-purpose code, which proceeds directly from surface specification to solution, is tested on problems taken from the literature.