Learning Forum

[obschti]

Hey there!

Currently I want to model a closed installation space with a heat source inside. Therefore I also have to consider radiation. My question is how can I find out a fitting radiation model? I think "S2S" is suitable in my case. The fluid in the installation space is argon. 

I red this page: https://www.afs.enea.it/project/neptunius/docs/fluent/html/th/node118.htm

It says that S2S is suitable for "non-participating media". How do I find out wheather my media I participating or not and what does this actually mean?

Thanks for advise!

[Karthik R]

If you don't have to account for absorption, scattering, or emission from the fluid media, then the fluid is non-participating. If you have to take these phenomena into account, then you might have to make the fluid participating. If this is the case, please use the DO model.

Calculating the optical thickness will help you decide whether you want to include some of these phenomena into your modeling. 

The following link might help. 

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/flu_th/flu_th_sec_rad_choosing.html?q=optical%20thickness

If you are looking for instructions on how to open the link, please find them here. 

https://forum.ansys.com/forums/topic/how-to-access-the-ansys-online-help/

If this answer is useful, please mark it as 'Is Solution' so it benefits others.

Thanks.

Karthik 

[obschti]

 Hi Karthik,

thanks for your help. This already helped a lot but I don't get exactly what you mean with your following sentence:

"Calculating the optical thickness will help you decide whether you want to include some of these phenomena into your modeling."

--> When I open up the link you sent me I find this:

"The DTRM, DO, and MC models work across the full range of optical thicknesses, but are substantially more expensive to use. Consequently, you should use the “thick-limit” models, P-1 and Rosseland, if the problem allows it. For optically thin problems (), the DTRM,DO, and MC models, only, are appropriate."

There are also no aL values when S2S is suitable. Do I have to take DO anyway if aL<1?

What unit has L?

Thanks!

[Karthik R]

L is in meters.

If you are not interested in these phenomena, I'd recommend that you use S2S. If you are interested, I'd suggest that DO is good. However, DO can be tricky to set-up and is computationally expensive.

I hope this clarifies.

[obschti]

All right, thank you very much!