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7.2
Development of surface emissivity (emissivity)
For thermally thick materials, the surface emissivity is computed as a mass-weighted sum of the individual
values of the emissivity in the first condensed phase grid cell. In this verification test, the initial material,
having emissivity of 1.0, is converted to another material, having emissivity of 0.0, at a constant rate of
0.1 s−1 . As a result, the surface emissivity should change linearly from 1.0 to 0.0 in 10 s.
1
Surface Emissivity (emissivity)
Emissivity
0.8
0.6
0.4
0.2
Analytical (Emissivity)
FDS (EMISSIVITY)
0
0
2
4
Time (s)
6
8
10
Figure 7.5: Testing the emissivity of solid materials.
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