WSGG radiation model

Kuljeet · August 2, 2022, 06:29

Hi, can I compute weighing factor and k value for each gray gas which ANSYS is simulating with in WSGG radiation model.
-K

alainislas · August 2, 2022, 12:05

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.

Kuljeet · August 6, 2022, 05:33

thank you for the reply. I have read that paper. if possible can you elaborate a little about using custom fields.
-K

alainislas · August 8, 2022, 14:04

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

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

-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 $\varepsilon_{i}$

jannothi · September 28, 2022, 07:37

thank you for the reply.

August 2, 2022, 06:29	WSGG radiation model	#1
Kuljeet New Member Kuljeet Singh Join Date: Aug 2022 Posts: 20 Rep Power: 4	Hi, can I compute weighing factor and k value for each gray gas which ANSYS is simulating with in WSGG radiation model. -K

August 8, 2022, 14:04		#4
alainislas Senior Member Alain Islas Join Date: Nov 2019 Location: Mexico Posts: 142 Rep Power: 7	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 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 -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 $\varepsilon_{i}$ shamcross likes this.

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August 2, 2022, 12:05		#2
alainislas Senior Member Alain Islas Join Date: Nov 2019 Location: Mexico Posts: 142 Rep Power: 7	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.

August 6, 2022, 05:33		#3
Kuljeet New Member Kuljeet Singh Join Date: Aug 2022 Posts: 20 Rep Power: 4	thank you for the reply. I have read that paper. if possible can you elaborate a little about using custom fields. -K

September 28, 2022, 07:37		#5
jannothi New Member jannothi Join Date: Sep 2022 Posts: 1 Rep Power: 0	thank you for the reply.