Consider two infinitely long thin concentric tubes of circular cross section as shown in the figure. If D1 and D2 are the diameters of the inner and outer tubes respectively, then the view factor F22 is given by
1
\(\left( {\frac{{{D_2}}}{{{D_1}}}} \right) - 1\)
2
Zero
3
\(\left( {\frac{{{D_1}}}{{{D_2}}}} \right)\)
4
\(1 - \left( {\frac{{{D_1}}}{{{D_2}}}} \right)\)