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#1 |
Senior Member
Onno
Join Date: Jan 2012
Location: Germany
Posts: 120
Rep Power: 15 ![]() |
Hello,
I am trying to simulate a mesh containing walls with y+-Values between 100 and 200, as well as walls with y+-Values well below 1 using kOmegaSST. Of course this is not really good to begin with but my idea was to use fixedValue for k and zeroGradient for omega on the walls with the low y+-Values. Unfortunately when I start the simulation the OpenFOAM seems to set the walltypes to wallfunctions on it's own. Is there some way to disable this? Kind regards Kaskade |
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#2 |
Senior Member
Onno
Join Date: Jan 2012
Location: Germany
Posts: 120
Rep Power: 15 ![]() |
Answer:
k type fixedValue; value 0; //some say you should use a value like 1e-11, but it doesn't seem to make any difference omega type zeroGradient; nut type calculated; value $internalField; If you don't set up a file for nut yourself, OpenFOAM will generate it and upgrade your walls with wallfunctions. |
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#3 | |
Senior Member
Huang Xianbei
Join Date: Sep 2013
Location: Yangzhou,China
Posts: 302
Rep Power: 14 ![]() |
Quote:
Why the nut is set to be calculated instead of zerogradient? I remember that when no wall function is needed, the type should be zerogradient. Please correct me if I'm wrong Xianbei |
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#4 |
Senior Member
Onno
Join Date: Jan 2012
Location: Germany
Posts: 120
Rep Power: 15 ![]() |
That was a long time ago.... right now I what say, you might as well leave the wall functions turned on and use nutUSpaldingWallFunction for nut.
@myself from 2,5 years ago: If your mesh is that bad/uneven -> fix that first. |
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#5 | |
Senior Member
Huang Xianbei
Join Date: Sep 2013
Location: Yangzhou,China
Posts: 302
Rep Power: 14 ![]() |
Quote:
Thank you for your reply. As omega based turbulence model can solve the finer mesh with y+<3 or less, so no wall function is needed when the mesh is fine enough. What do you mean by saying 'turn on the wall function as well'? Xianbei |
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#6 |
Senior Member
Onno
Join Date: Jan 2012
Location: Germany
Posts: 120
Rep Power: 15 ![]() |
In my original post I was asking for a way to turn of the wall function manually on walls with a small y+. But from I understand now, you don't need to turn off the wall functions, since omegaWallFunction and nutUSpaldingWallFunction can be used for small y+-values.
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#7 | |
Senior Member
Huang Xianbei
Join Date: Sep 2013
Location: Yangzhou,China
Posts: 302
Rep Power: 14 ![]() |
Quote:
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#8 |
Senior Member
Onno
Join Date: Jan 2012
Location: Germany
Posts: 120
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It think it is discussed here: http://www.cfd-online.com/Forums/ope...megasst-2.html
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#9 | |
Senior Member
Huang Xianbei
Join Date: Sep 2013
Location: Yangzhou,China
Posts: 302
Rep Power: 14 ![]() |
Quote:
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