[jfox]

Does anyone know if there is a way to implement symmetry boundary condition for radiation models viewFactor and (especially) fvDOM?

Setting the boundaries to "symmetry" does not lead to the right result.

All answers and ideas are welcome!

[zfaraday]

Hi,

My guess is that the way to proceed may be to set the symmetry patches as "patch" instead of "symmetryPlane" and set emissivity as 0 for G and IDefault variables in the case of fvDOM. The symmetry condition for T would be "zeroGradient" since it should have the same effect than "symmetryPlane".

This is my idea but the problem is that I already tried it in a cylindrical case I'm working on, I divided the full cylinder to work only with a quarter of it and the results are not consistent compared with the full case. Temperature distributions are similar qualitatively, but the symmetrical case gives higher values of temperature (like 12-15K more or less, now I don't remember exactly). I don't understand that difference, if anyone knows the proper way to set up a symmetrical case with radiation I would really appreciate an answer. I don't know if I missed something in my specification or if it's not possible to specify a symmetry plane when radiation must be taken into account.

Many thanks in advance.

Regards,

Alex

[zfaraday]

No hints or suggestions so far. Does anyone know how to tackle a symmetry case with radiation? Or is it not possible to define symmetry conditions in this kind of cases by now?

Many thanks in advance.

Alex

[jfox]

Hi Alex,

I think the problem with setting the emissivity to 0 is, that all the BCs are diffusive-radiation BCs. For the wedge of a cylinder you could use cyclic BCs (I tried this but I was not able to reach convergence for radiation calculation)



If someone finds a solution, I am still interested

Josef

[chriss85]

jfox, do you think the diffusive boundaries are also a problem for the P1 model?

[jfox]

Yes, I think so. But to clarify that without doubt, I suggest to set up a little testcase.

[xuhuang]

Hi,

Anyone solved the problem?
I also have the same problem with OF-2.3.1. I added radiation in ractingFoam. When using full geometry (3D), it works well with both P1 and fvDOM model. But when I try to use half or quarter of the geometry setting with symmetry or symmetryPlane boundary, it crashes.

People say that the view factor model does not support symmetry-BCs at all.

http://www.cfd-online.com/Forums/ope...ification.html

Does it mean I have go back to full geometry? But the grid size will increase a lot!
Any ideas?
Thanks a lot.

Cheers,
Xu

[dasith0001]

Hi,

I know this is a very old thread but as of now, it seems like 'openfoam2306' let fvDOM to run with both symmetry and axisymmetry conditions.

https://doc.openfoam.com/2306/tools/processing/boundary-conditions/rtm/derived/thermal/specularRadiation/

I have a wedge BC conditions and I want to run CHT case in both transient and Pseudo ( localEuler) with radiation. my issue is,

-V12 allows to run psedo but not fvDOM with wedge BC.
-openfoam2306 allows to run fvDOM with wedge BC but not Pseudo

I would highly appreciate if one can suggest to have this both worlds at same time ?

Thanks,
Dasith