Define vacuum conditions

Cartuns11 · June 29, 2015, 12:56

Hi everybody,

I'm working on a radiation model using chtMultiRegionSimpleFoam (fvDOM). One region has to be vacuum, but I don't know how define it. This region is between two solids ( solid1_to_vacuum and solid2_to_vacuum), and the most important factor is the radiation has been emitted by solid1.

I don't know how introduce, in the region has been called "vacuum", the vacuum conditions or properties ( thermophisicalProperties, .....).

I thought that I could change thermal coefficients.......I changed it to 0....but it did not work.

could anyone help me?

Thanks!!

RodriguezFatz · June 30, 2015, 03:47

Without knowing much about your case: Did you try to set it to something really, really low but not zero? Such as 1e-10 ? Sometimes OpenFoam divides by these factors and you get a problem when setting it to "0".

coccone · July 2, 2015, 11:16

I'm working on a chtMultiRegion case too and I am desperately trying to set up radiation modelling. I preferred to try first with viewFactor instead of fvDom for CPU purposes to no avail so far. In my case, as I have a huge mesh for a quite complex geometry I would not want an additional vacuum field to be calculated.

Since radiation is the only heat transfer through vacuum one would expect it to be possible...

Has anyone suggestions on how to proceed?

PS: I already checked this thread http://www.cfd-online.com/Forums/ope...ng-vacuum.html but I am not so skilled to modify the solver!

June 29, 2015, 12:56	Define vacuum conditions	#1
Cartuns11 New Member Join Date: May 2015 Location: Barcelona Posts: 24 Rep Power: 11	Hi everybody, I'm working on a radiation model using chtMultiRegionSimpleFoam (fvDOM). One region has to be vacuum, but I don't know how define it. This region is between two solids ( solid1_to_vacuum and solid2_to_vacuum), and the most important factor is the radiation has been emitted by solid1. I don't know how introduce, in the region has been called "vacuum", the vacuum conditions or properties ( thermophisicalProperties, .....). I thought that I could change thermal coefficients.......I changed it to 0....but it did not work. could anyone help me? Thanks!!

June 30, 2015, 03:47		#2
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 27	Without knowing much about your case: Did you try to set it to something really, really low but not zero? Such as 1e-10 ? Sometimes OpenFoam divides by these factors and you get a problem when setting it to "0". __________________ The skeleton ran out of shampoo in the shower.

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July 2, 2015, 11:16		#3
coccone New Member Join Date: Mar 2015 Location: Earth yet Posts: 25 Rep Power: 11	I'm working on a chtMultiRegion case too and I am desperately trying to set up radiation modelling. I preferred to try first with viewFactor instead of fvDom for CPU purposes to no avail so far. In my case, as I have a huge mesh for a quite complex geometry I would not want an additional vacuum field to be calculated. Since radiation is the only heat transfer through vacuum one would expect it to be possible... Has anyone suggestions on how to proceed? PS: I already checked this thread http://www.cfd-online.com/Forums/ope...ng-vacuum.html but I am not so skilled to modify the solver!