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k/omega boundary condition changed after decomposePar |
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January 31, 2016, 08:26 |
k/omega boundary condition changed after decomposePar
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#1 |
Member
Yage
Join Date: May 2014
Posts: 60
Rep Power: 11 |
Dear All,
I set the boundary condition for k/omega for walls, such as for k: Code:
dimensions [0 2 -2 0 0 0 0]; internalField uniform 0.04; boundaryField { frontAndBack { type symmetry; } inlet { type fixedValue; value $internalField; } ... walls { type kqRWallFunction; value uniform 0; } } Code:
boundaryField { frontAndBack { type symmetry; } inlet { type fixedValue; value nonuniform 0(); ... blade { type kqRWallFunction; value uniform 0.04; } ... } Regards, Yage |
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January 31, 2016, 13:23 |
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#2 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
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Quick answer: It's not a problem, it's a counter-measure to avoid shooting one's own foot.
"kqRWallFunction" is a boundary condition that is calculated by OpenFOAM itself and the provided value is for post-processing purposes. If you were using 0, the solver would crash in the first iteration, because somewhere it would try to do a division by k=0.
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Last edited by wyldckat; January 31, 2016 at 18:01. Reason: "try to a" --> "try to do a" |
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January 31, 2016, 16:28 |
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#3 |
Member
Yage
Join Date: May 2014
Posts: 60
Rep Power: 11 |
Dear Bruna,
thanks for your reply. But the non-zero value will be also changed to internal field value, such as I use 1 instead of 0 for k at walls |
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January 31, 2016, 20:05 |
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#4 |
Senior Member
Join Date: Aug 2013
Posts: 407
Rep Power: 15 |
Hi,
If you have specified a non-zero value for the value, then OpenFOAM would not change it to the internalField value. My guess is that OpenFOAM replaces the value with internalField value (when the original value is zero) because it is the simplest estimate it can make based on the information it has. Hope this helps. Cheers, Antimony |
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February 4, 2016, 03:54 |
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#5 | |
Member
Yage
Join Date: May 2014
Posts: 60
Rep Power: 11 |
Quote:
Sorry for the later reply. My openfoam version is 2.3.0 and the omega boundary value will change to internalfield value after decompose. But both of the values are non-zero. This is very strange. One more question: If I refine the mesh with added layers (y+<6), so that I dont need the wallfunction. then I should use fixedValue with uniform value=1e-10 for both k and omega, is that correct? Regards, Yage |
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