Calculation of Occluded Diffuse and Nondiffuse Radiative Exchange Form Factors

Abstract

A procedure is described to calculate the radiative exchange form factor between polygons. The spatial distribution of the emitting surface can be arbitrary and occluding surfaces are taken into account. Emitted radiant power is discretized into collimated, homogeneous beams leaving in a three-dimensional, angular spray. Since a beam is homogeneous, the flux transported to a receiving surface is proportional to the intersection area of beam and surface. Occluding surfaces change the shape of the areas of intersection by casting collimated shadows. The total radiant power transported is proportional to the sum of the areas of intersection of all beams. Test cases are presented that demonstrate the utility and accuracy of the procedure and compare the computational expense with ray casting.

Keywords:

• radiant exchange
• form factors
• polygons
• occlusion