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Old   August 2, 2022, 06:29
Default WSGG radiation model
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Kuljeet Singh
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Hi, can I compute weighing factor and k value for each gray gas which ANSYS is simulating with in WSGG radiation model.
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Old   August 2, 2022, 12:05
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Alain Islas
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In Ansys Fluent, the default WSGGM coefficients are the ones shown in Smith et al. 1982 (https://doi.org/10.1115/1.3245174). You can use temperature to create a custom field to plot/show the weighting factors and the absorption coeffiients for each gray gas.
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Old   August 6, 2022, 05:33
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thank you for the reply. I have read that paper. if possible can you elaborate a little about using custom fields.
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Old   August 8, 2022, 14:04
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In the WSGGM model, the emissiity weighting factors \alpha_{\varepsilon} are expressed as a polynomial function of temperature of order N_{g} , i.e.

\alpha_{\varepsilon,i}(T)=\sum_{j=0}^{N_{g}}b_{\varepsilon,i,j}T^{j}

where N_{g} is the number of gray gases (3 in the work of Smith et al. 1982). For example in Table 1, for a mixture with MR = 2.0 you have

\alpha_{\varepsilon,1}(T)=6.508\times 10^{1} - 5.551\times 10^{4}\cdot T + 3.029\times 10^{7}\cdot T^{2} - 5.353\times 10^{11}\cdot T^{3}
\alpha_{\varepsilon,2}(T)=-0.2504\times 10^{1} + 6.112\times 10^{4}\cdot T - 3.882\times 10^{7}\cdot T^{2} + 6.529\times 10^{11}\cdot T^{3}
\alpha_{\varepsilon,3}(T)=2.718\times 10^{1} - 3.118\times 10^{4}\cdot T + 1.221\times 10^{7}\cdot T^{2} - 1.612\times 10^{11}\cdot T^{3}

I believe if you read Fluent User Manual you can easily type above expressions in the dialog box of the custom field expression, create such fields and later postprocess them (contours, lines, probes, etc...)

Then, what else you want to plot? 1) the absorption coefficients k_{i} ? or 2) the i-th emissivities \varepsilon_{i} ?
If its the first case, they are already shown in Table 1 (2nd column). If its the second, you can use Eq. (1) to create corresponding field expressions for each \varepsilon_{i}
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Old   September 28, 2022, 07:37
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thank you for the reply.
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