Element on longitudinal strip on inside of right circular cylinder to the exterior of concentric smaller right circular cylinder.
FDiff_13 (r1, r2, z, h) provides the view factor from a differential element (1) on a longitudinal strip on the inside of right circular cylinder with radius r2 to the exterior of a smaller concentric right circular cylinder (2) with radiation r1.
Inputs:
r1 is the radius of the smaller cylinder [m or ft]
r2 is the radius of the larger cylinder [m or ft]
z is the height of the element above the base [m or ft]
h is the height of the cylinders [m or ft]
Example:
$UnitSystem SI K Pa J deg
"The following program compares the integrated view factor between the inside of a cylinder with its base to the more direct result from F3D_4. "
r1=0.5 [m]
r2=1 [m]
h=2 [m]
F_12=integral(FDiff_13(r1,r2,z, h)*2*pi*r2,z,0,h)/(2*pi*r2*h)
F_12`=F3D_4(r1, r2, h)*r1/r2 "note use of reciprocity"
{Solution: F_12 = F_12` = 0.4126}
Reference: Howell, http://www.me.utexas.edu/~howell/sectionb/B-57.html