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[Other] Cyclic mesh for fully-developed profile |
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#1 |
Member
Join Date: Nov 2011
Posts: 44
Rep Power: 14 ![]() |
Hello
I am trying to find the fully developed velocity profile in a straight duct. Rather than compute a 3D duct, and look at its profile towards the end, I would like to apply periodic boundary conditions to make it more efficient. I have never done this on openFOAM and would like some help. I have a inlet and an outlet boundary. So: boundary ( inlet { type cyclic; neighbourPatch outlet; faces ( (0 4 7 3) ); } outlet { type cyclic; neighbourPatch inlet; faces ( (2 6 5 1) ); However, now I am wondering what kind of boundary field definitions I need. Previously I had zeroGradient or fixedValue fields (depends on variable) for both the inlet and outlet. What do I need to set for the periodic case? Thank you very much. Kindest Regards, F |
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#2 |
Senior Member
Steven van Haren
Join Date: Aug 2010
Location: The Netherlands
Posts: 149
Rep Power: 16 ![]() |
Take a look at the channelFoam tutorial. This will help you I think.
Please keep in mind that the pressure field is never periodic. Therefore you will have to split the pressure field in a periodic part and a pressure drop. This can be seen in the channelFoam solver. |
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#3 |
Member
Join Date: Nov 2011
Posts: 44
Rep Power: 14 ![]() |
I see..
So, it means that I need to modify my solver? Looking at channelFoam.c, I would need to slightly change the first part before the PISO loop and add the section correcting the driving force for a constant mass flow rate. I would not need to change any field definitions, apart from creating createGradP.H, is that correct? In the first section, what is "sgsModel->correct(); " ? Kindest regards, Francesco |
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#4 |
Senior Member
Steven van Haren
Join Date: Aug 2010
Location: The Netherlands
Posts: 149
Rep Power: 16 ![]() |
That you can do indeed, or you can use a jumpcyclic. This has different names for different OF versions I think. Browse around the OF source to see the difference.
src » finiteVolume » fields » fvPatchFields The same holds for sgsModel->correct(); Browse around the turbulence models to see what it does. src » turbulenceModels |
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#5 |
Member
Join Date: Nov 2011
Posts: 44
Rep Power: 14 ![]() |
Hmm, I don't quite understand how jumpCyclic works (especially trying to read the source code).. Is there a tutorial on how to use it?
There is a fan tutorial in OF that apparently uses it but I'm not sure how that is relevant to what I'm trying to do... Kind Regards, F |
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#6 | |
Senior Member
Jian Zhong
Join Date: Feb 2012
Location: Birmingham
Posts: 109
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Quote:
I also met the same problem that I want to set zeroGradient or fixedValue fields (depends on variable) for both the cyclic inlet and outlet. Did you find a way to achieve it? My best regards, Jian |
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Tags |
cyclic boundaries, openfoam, periodic boundary |
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