function [F12, A1, F21, A2] = plate2plate(a, b, c) %[F12, A1, F21, A2] = plate2plate(a, b, c) % % Description: % % View factor between two coaxial rectangular surfaces. % % Inputs: % % a = width of rectangle surface % b = depth of rectangle surface % c = distance between the two surfaces % % Outputs: % % F12 = view factor from lower rectangle to upper rectangle % A1 = area of the lower rectangle % F21 = view factor from upper rectangle to lower rectangle % A2 = area of the upper rectangle % % Reference: % % A Catalog of Radiation Heat Transfer Configuration Factors, % third edition, John R. Howell, The University of Texas at Austin % C-11: Identical, parallel, directly opposed rectangles. % http://www.thermalradiation.net/calc/sectionc/C-11.html % %========================================================================== if c <= 0.0 error('FATAL ERROR in plate2plate: distance between the plates, c = %d, must be greater than zero.',c) end A1 = a*b; % lower plate area A2 = A1; % upper plate area X = a/c; Y = b/c; F12 = (2/(pi*X*Y))*(log(sqrt(((1 + X^2)*(1 + Y^2))/(1 + X^2 + Y^2))) ... - X*atan(X) - Y*atan(Y) + X*sqrt(1 + Y^2)*atan(X/sqrt(1 + Y^2)) ... + Y*sqrt(1 + X^2)*atan(Y/sqrt(1 + X^2))); F21 = F12*A1/A2; % F12*A1 = F21*A2