# Problem with "symmetryPlanne" boundary condition

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March 12, 2012, 13:30
Problem with "symmetryPlanne" boundary condition
#1
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Felipe
Join Date: Feb 2011
Posts: 9
Rep Power: 8
Hi everybody,

I have a problem when I set a boundary condition as a "symmetryPlanne". I'm trying to solve the radiation and convection heat transport inside enclosures, to do this I'm using the solver buoyantSimpleRadiationFoam, everything works fine meanwhile Idon't set a boundary condition as a symmetryPlane. I'm using version 1.7.1

To actually see if this was the problem, I solved a very simple case which is attached. It consists of a rectangle whose base wall has a fixed temperature of 400 K and an emissivity of 0.7, the others walls have a fixed temperature of 600 K and an emissivity of 0.9. When I solve all the geometry there is not problem, this means that the overall heat balance is conserved and the results are the same as the ones calculated using other methods.

When I define a symmetryPlane for the left wall and reduce the length to the half, the results are not the same as before. Here I would have expected that just multiplying the results by 2 I would get the same results as before but not. Even more, in this case there is not heat conservation, that means that the addition of the heat by radiation (Qr field) over the walls is not 0!

Well, I don't know what I'm doing wrong , I hope somebody help me to see it.

Regards,
Felipe
Attached Files
 rectangle.tar.gz (33.8 KB, 2 views)

Last edited by fcuevas; March 16, 2012 at 10:13.

 March 14, 2012, 06:07 #2 New Member   Felipe Join Date: Feb 2011 Posts: 9 Rep Power: 8 Any clue??? The best approach I've done is instead of defining a symmetry plane is define a no emissive surface, that in the case of the radiation would act as a mirror. The solution is not exact, there is an error of approximately 5% but I could live with that... This works well for the radiation transport but will affect the convection transport. Anyway I still have the doubt if I'm using correctly the symmetry plane or maybe I'm not doing correctly the postprocessing or... I don't know what could be wrong.... All the tips are welcome!! Regards,

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