function [F12, A1, F21, A2] = disk2disk(r1, r2, h) %[F12, A1, F21, A2] = disk2disk(r1, r2, h) % % Description: % % View factor between two coaxial disks. % % Inputs: % % r1 = radius of upper disk % r2 = radius of lower disk % h = distance between the disks % % Outputs: % % F12 = view factor from upper disk to lower disk % A1 = area of the upper disk % F21 = viewfactor from lower disk to upper disk % A2 = area of the lower disk % % Reference: % % A Catalog of Radiation Heat Transfer Configuration Factors, % third edition, John R. Howell, The University of Texas at Austin % % http://www.thermalradiation.net/sectionc/C-41.html % %========================================================================== R1 = r1/h; R2 = r2/h; X = 1.0 + (1.0 + R2^2)/(R1^2); A1 = pi*r1^2; % Upper disk area A2 = pi*r2^2; % Lower disk area F12 = (X - sqrt(X^2 - 4.0*(R2/R1)^2))/2.0; F21 = F12*A1/A2; % F12*A1 = F21*A2