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Negative Temperature chtMultiRegionSimpleFoam + thermalBaffle1D + Radiation |
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October 21, 2017, 01:10 |
Negative Temperature chtMultiRegionSimpleFoam + thermalBaffle1D + Radiation
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#1 |
Member
Jaydeep
Join Date: Jun 2015
Posts: 34
Rep Power: 11 |
Hello everyone,
I pieced together stuff from the generous help from Tobias and Alex to create a test case. It is a very simple problem where you have 2 solids (isotropic), in air. There is a vertical wall next to the second solid, created as thermalBaffle1D. Everything works fine until you introduce baffle. After adding baffle, the temperature in the baffle goes negative (reduces below ref value and indefinitely reduces until simulation crashes). I don't know what is exactly happening here. While testing for radiation, I discovered that in openfoam-dev "qr" option in baffle boundary doesn't affect anything? It still has to be specified as "Qr". @Tobi @zfaraday - you will probably have an answer to this question - this example borrows stuff from your axisymmetric meshing and circuitBoardCooling_rad tutorials respectively. Many thanks! |
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October 21, 2017, 02:01 |
Updates
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#2 |
Member
Jaydeep
Join Date: Jun 2015
Posts: 34
Rep Power: 11 |
Please note that createBaffles need to be run separately. There's an error in nut patch entry for baffles -- remove compressible::
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October 21, 2017, 02:20 |
snGrad scheme
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#3 |
Member
Jaydeep
Join Date: Jun 2015
Posts: 34
Rep Power: 11 |
Note:
I suspected for a while using uncorrected scheme for sngrad in solid regions could be a reason. Changed it to corrected -- negative temperature seems to have gone away. I will confirm full resolution tomorrow. |
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October 21, 2017, 02:38 |
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#4 |
Member
Jaydeep
Join Date: Jun 2015
Posts: 34
Rep Power: 11 |
Problem solved.
It was snGrad scheme in fact. |
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November 23, 2017, 20:48 |
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#5 |
New Member
Franco
Join Date: Sep 2015
Location: Montreal
Posts: 26
Rep Power: 11 |
Thank you for your post! I don't know if this could be helpful, but I'd like to add that from OF4.1 to OF5.0, the developers changed the variable Qr (OF4) to qr (OF5).
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Tags |
baffles, chtmultiregionsimplefoam, heat and mass transfer, radiation model |
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