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Adding Radiations in chtMultiRegionSimpleFoam

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Old   August 5, 2021, 04:29
Default radiation source
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it seems we need to change the energy equation for solid region. in OF7.0, enthalpy is adopted to solve the energy equation, but in OF8.0, only internal energy could be adopted to solve the energy equation. I tried to add the radiation source term to the solid energy equation, but there always exists something wrong. so can we add the radiation term to the solid energy equation using the internal energy form?

Originally Posted by peterhess View Post
Trying to execute the case using OF7.0 I recognized, that some syntax changes has been made.
I modified the case to work on OF7.0.
See attached file.
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Old   September 21, 2021, 05:42
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I don't know much relevant it is in this thread but can anyone guide how to introduce UV radiation boundary conditions in chtMultiRegionSimpleFoam? As in a UV lamp?

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Old   October 4, 2023, 03:24
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Originally Posted by peterhess View Post
I applied opaqueSolid to fluid region in my example and can confirm that this model is applicable for fluid.
I know I am so late to this party, but your single line of comment has sent me into a deep rabbit hole of exploration.

The issue is, once I applied opaqueSolid radiation model to fluid, and no matter what parameter I change in the radiationProperty file/s, the temperature do not change in any of my solids. Note that the solid radition is also set with opaqueSolid.

I am really thinking if the the opaqueSolid can be use in the fluid region, if yes, what it is actually doing ?

Any suggestions to clear my confusion is much appreciated.

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Old   October 5, 2023, 12:52
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Hello and sorry for the late answer!

Well, the problem, as I remember, since it is a while that the topic was in discussion, is that turning on the radtiation in one region in the simulation make it necessery to turn it on in all other regions.

At least it was the case in the past. I dont know if it still the same in the newer versions of OF...

Now suppose you want to neglegt the radiation in a specefic region and calculate it in others, in this case you need to define a radiation calculation model in the region, that you dont want it to recognize radiation.

In this case, you can apply opaqueSolid as a model in this region regardless if it is solid or fluid.

That is where this radiation model comes handy.

I suggest the following to confirm this opinion (I might be wrong...).

Take a tutorial that is multi regions and have radiation and turn the radiation in one of the regions off, letting the other regions turned on.

You will see, I hope , that you will get an error massage.

Then turn the radiation in this region on and use the opaqueSolid model, you will see that the error massage is disappiers.

By furthor opening points I will be glad to discuss with you.


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Last edited by peterhess; October 6, 2023 at 21:30.
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Old   October 8, 2023, 20:20
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You are not late at all and thank you for taking your time to reply.
There is no discussion at all on 'OpaqueSolid in FluidRegion' so your suggestions are much appreciated.

I've been testing this for a while with the attached 'test' case.

Note that I am using OF7.
And it runs without error even if I switch 'off' radiation in fluid region.

I've tested this with varied 0-1 emissivities and absorbsivities but all the time I get identical results, even with 'switch off' radiation in the fluid!!!!

With the same set-up, If I changed to 'P1 radiation model' in the fluid, then only I have control with emissivity and absorptivity.

I am confused why 'OpaqueSolid' radiation model do not respond any of the changes in absorptivity and emissivity parameters.

Correct me if I am wrong, the OpaqueSolid will not solve radiation inside the region but only at the boundary. So if I change the radiation properties at the boundary, in 'boundaryRadiationProperties' file, why does it not effect the results ?

Thank you
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chtmulitregionfoam, chtmultiregionsimpefoam, openfoam, radiation

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