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level set and thermal radiation or conduction

Posted Apr 28, 2011, 2:20 p.m. EDT Fluid & Heat, Heat Transfer & Phase Change, Computational Fluid Dynamics (CFD) Version 4.1 4 Replies

Navid Asadiznajani
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Hi everybody



I have a problem. using level set method (although i am still in trouble with level set) I was wonder how we can add heat transfer analysis to it?

so if we do a laminar two phase flow, level set and want to know the temperature or (heat radiation in my case) is it not doable :(

I was thinking I can add physic 'heat transfer with surface to surface radiation" physic to it and do simulation with them. do you think it is doable?

like the hot fluid flows in a canal then the boundary of the canal gets heated by that as the hot fluid flows and heat energy diffuses as conducts or radiation in the block connected to the canal.

how is it doable? is it.

Thanks in advance
4 Replies Last Post Apr 29, 2011, 3:18 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 28, 2011, 2:50 p.m. EDT
Hi

I'm afraid that it is not implemented, by default, at least in my understanding, as radiation exchange requires "physical" boundaries for the view factor estimations, while the level set is based on "virtual boundaries" (my understanding again). So I believe you would need to implement your own radiation physics, or at least find a way to link it over to a model that respects COMSOL's default way to treat radiation exchange.

Pls note that this is my understanding, I might be wrong ;)
so you could check with "support" to get a more definitive answer.

However I believe that conduction heat exchange can probably be easier implemented, if not already so.

--
Good luck
Ivar
Hi I'm afraid that it is not implemented, by default, at least in my understanding, as radiation exchange requires "physical" boundaries for the view factor estimations, while the level set is based on "virtual boundaries" (my understanding again). So I believe you would need to implement your own radiation physics, or at least find a way to link it over to a model that respects COMSOL's default way to treat radiation exchange. Pls note that this is my understanding, I might be wrong ;) so you could check with "support" to get a more definitive answer. However I believe that conduction heat exchange can probably be easier implemented, if not already so. -- Good luck Ivar
Navid Asadiznajani
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Posted: 1 decade ago Apr 28, 2011, 3:34 p.m. EDT
Hi Ivar

thank you again. so you said conduction is not included too right?
so by implementing you mean to link it to MATLAB and right codes for it? i have never done that before. and actually my MATLAB coding is not good somehow.

so conduction is also not possible either? and you mean when we use laminar two phase flow other physics can not be added right? even if just a block in connection and get heat from conduction (I assume maybe I can get radiation from the connected box if it COMSOL considers the connected box in STSR environment)

what is your opinion?


Hi Ivar thank you again. so you said conduction is not included too right? so by implementing you mean to link it to MATLAB and right codes for it? i have never done that before. and actually my MATLAB coding is not good somehow. so conduction is also not possible either? and you mean when we use laminar two phase flow other physics can not be added right? even if just a block in connection and get heat from conduction (I assume maybe I can get radiation from the connected box if it COMSOL considers the connected box in STSR environment) what is your opinion?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 28, 2011, 4:20 p.m. EDT
Hi

No I cannot say that conduction is not included, I would have to dig into the doc about level set method again in V4 (havent used it here yet) but I believe conduction is easier than radiation so it might be there already or to come ;)
Again check with support to be sure

I hardly use Matalb in V4, I find I can really do everything (almost) within the GUI's

--
Good luck
Ivar
Hi No I cannot say that conduction is not included, I would have to dig into the doc about level set method again in V4 (havent used it here yet) but I believe conduction is easier than radiation so it might be there already or to come ;) Again check with support to be sure I hardly use Matalb in V4, I find I can really do everything (almost) within the GUI's -- Good luck Ivar
Navid Asadiznajani
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Posted: 1 decade ago Apr 29, 2011, 3:18 p.m. EDT
Hi again

another question maybe repeated one but wanted to be sure

as i found recently, field of view is not included in COMSOL so in surface to surface irradiation just hemicube method and direct angle method are applicable. and if you want to say for example a surface has just a 70 degree for its field of view you can not define it in COMSOl right? just to confirm.

the only way is to model other objects in neighborhood to limit the filed of view but in this case you will have radiation from those surfaces even you define them as 0 or 1 for emissivity. right? so overall field of view is NOT applicable in COMSOL, is it true?

so is this what it is or I missed something?

Thanks
Hi again another question maybe repeated one but wanted to be sure as i found recently, field of view is not included in COMSOL so in surface to surface irradiation just hemicube method and direct angle method are applicable. and if you want to say for example a surface has just a 70 degree for its field of view you can not define it in COMSOl right? just to confirm. the only way is to model other objects in neighborhood to limit the filed of view but in this case you will have radiation from those surfaces even you define them as 0 or 1 for emissivity. right? so overall field of view is NOT applicable in COMSOL, is it true? so is this what it is or I missed something? Thanks

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