[volleyHC]

Hey Folks!

I need some help finding the right boundary conditions for my simulation. I want to simulate a fluid flow in a pipe. that pipe should be heated just only by radiation, but i want a parallel/oriented radiation, not a diffuse. So I mean like radiation from the sun; but i don't want to model the sk/athmosphere for that, just the pipe.
And thats exactly the point whre I am unsure. If i am right, the boundary conditions, like Marshak Radiation are for diffuse radiaition.

Hope u guys can help me with that!

Kind regards,

volleyHC


(sorry for eventual misspelling - no native english speaker )

[zfaraday]

Hi volleyHC!

I'm not sure if I understood well what you need, you should have been more precise in the information you provided. However, I think I got it. Your system is a pipe and a fluid flowing through it, or maybe only the fluid, I don't know what are exactly your intentions.... Then, this pipe receives radiation in its external surface coming from the atmosphere, for instance....

If this is the situation, MarshakRadiation won't do the trick for you because you are not modelling the media which radiation travells through. Besides that, as you point out, it is diffusse radiation BC.

If I really predicted well your problem, I think I have to tell you that such BC doesn't exist yet in OpenFOAM because a while ago I tried to model a system similar to yours (but simpler, I guess) and I couldn't find the way on my own. However, something could be done by using groovyBC, but finally I never tried... Maybe someone else braver than me can shed a little more light on this issue.

I'm Sorry that I cannot be more useful...

Best regards,

Alex

[volleyHC]

Thanks for your response!
Well, its sometimes a bit difficult to be more precise, if you are not a native speaker. You just don't find the right words etc sometimes.
However, I guess, your get it, almost at least. So I try to specify it a bit.

My model is just the fluid-flow in the pipe, and it should be heatet via oriented radiation from outside.

Well and I also already feared, what you wrote, that Marshak BC won't work fot it and even that OpenFoam don't have the right BC for it.
But I dont really want to make my Model bigger and/or more complex and modeling the media which radiation travels through.

Anyway, many thanks, maybe your clue for groovyBC will help. I will have a look and try it out!
And I am also still very thankful, if anybody else has a few hints for me!

Kind regards,

volleyHC