a. Temperature contours.
b. Stream lines.
Figure 12. FECOME results for a vertical square enclosure at Rayleigh number 105.
960R
660R
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19
18
17
16
15
14
13
21
12
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10
24
9
1
2
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4
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960R
660R
0.25 ft
Figure 13. Grid used for comparing viewfactors and radiation heat flux calcu-
lations.
shown are the values submitted by Gartling (to de Vahl Davis and Jones). Gartling
used a model similar to FECOME, but with a different mesh. Figure 12 shows the
isotherms and streamlines for a Rayleigh number of 105; these agree well with those
presented by de Vahl Davis and Jones (1983).
Radiation viewfactor calculations obtained using the computer program
FEVIEW were checked by constructing a relatively simple mesh (Fig. 13) and
using viewfactor algebra and tables of viewfactor equations (Siegel and Howell
1992) to determine the viewfactors both manually and using FEVIEW. Results of
this analysis are shown in Table 3. Good agreement was obtained.
Implementation of the radiation heat flux boundaries was checked by solving
eq 113 for the heat fluxes through each of the surfaces in Figure 13. A shell around
the FECOME subroutine RADIATE was used for the input/output requirements.
The manual solution (the solution of the simultaneous equations was obtained
using a spreadsheet) is compared with the computer solution in Table 4; good agree-
ment can be seen.
23
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