Simpler view factor calculations for mutually perpendicular rectangles

Abstract

A foolproof formula and a simple-to-use approach are presented for the analytical calculation of view factor between two rectangles in mutually perpendicular planes. At present, the options available are: (a) a direct formula that is difficult to work with in general and unusable for particular cases; or (b) case-specific formulas that arise out of complicated view factor algebra manipulations. Tasked with such a view factor calculation and without case-specific view factor relations readily available, a user who is unable to derive them would be in a predicament. The proposed formula and the general calculation approach to be followed address these limitations. They are simple to adopt and the required calculation steps can be intuitively visualized by the user. As an added advantage, the proposed formula can be extended to derive other view factor relations for strips and rectangles in perpendicular planes. By all indications, some of these relations are unavailable in the literature at present.