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November 9, 2010, 13:13 |
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#41 |
Member
N. A.
Join Date: May 2010
Posts: 64
Rep Power: 16 |
Hi Frnasje, Eugene and others,
Are there any guideline of selecting the offset plane value, for example how far from the inlet? Thanks, Nir |
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November 10, 2010, 11:51 |
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#42 | |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Hello Andrea,
The definition you show here, from your ./constant/polyMesh/boundary file, is fine to use with the nearestCell keyword. If you want to use the nearestPatchFace keyword, you will have to specify a sample patch to the samplePatch switch, instead of none. I also understand that there is a bug under investigation associated with the use of the nearestFace keyword. Let me know if this solves your problem. Kind regards, Francois. Quote:
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November 10, 2010, 12:00 |
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#43 |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Yes, there are.
You might want to read the following papers:
I hope this helps, and good luck. Kind regards, Francois. |
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November 10, 2010, 12:57 |
Update to the use of nearestFace
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#44 |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Update to the use of nearestFace
The bug related to the use of the nearestFace keyword has been fixed in the 1.7.x release. If you are using the 1.7.x version of OpenFOAM, go to the ./OpenFOAM-1.7.x map, and enter: Code:
git pull Code:
./Allwmake Francois. |
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November 11, 2010, 05:21 |
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#45 | |
New Member
Andrea Aprovitola
Join Date: Nov 2009
Posts: 16
Rep Power: 17 |
Dear Francois,
I'm very grateful to you for your support, it s all clear to me and my application is working now Kind Regards, Andrea Quote:
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November 30, 2010, 09:31 |
free planar jet
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#46 |
Member
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Hi
I am using pisofoam and I want to model a three dimentional free planar jet with large eddy simulation. the co-flow velocity in my case is weak compared to the jet centerline velcity resulting in a strong shear layer at the jet edge. 1- can I use direct map method for turbulet inlet generation? 2- does any body use priodic boundary condition in OF? I really appreciate any help !! sincerely yours |
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November 30, 2010, 11:45 |
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#47 |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Dear Yashar,
Yes, you can use DirectMapped method for turbulent flow generation. That's what is was developed for. Whether you can apply it to your jet flow case is an other question. Maybe you can get away with a random turbulent inlet, as your case is somewhat similar to a flow over a backward facing step, for which the quality of the initial turbulence if of less importance. You should refer to relevant literature over the influence of the quality of turbulent information at the inlet for different flow cases. Think of Lund etal 1998, Keating and Piomelli 2004, etc. Yes, cyclic BC are used in OpenFOAM. Have a look at the channelFoam tutorial. Kind regards, Francois. |
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November 30, 2010, 12:01 |
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#48 |
Member
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Dear Francois,
I am really grateful for you guidance. I will study those papres. sincerely yours, Yashar |
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January 10, 2011, 04:19 |
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#49 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
Dear Fransje,
I use directMappedVelocityFlux to recycle the velocity field, but the flow field can not develop at all. After some steps, the velocity in the whole field is nearly zero. I use "pisoFoam" solver, Smagorinsky SGS model. I want to know how to make flow field develop using directMapped method ? or directMapped method must be used for channelFoam ? Thanks. |
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January 10, 2011, 10:34 |
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#50 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
I run the "pitzDailyDirectMapped" tutorials. I initialize the flow field using Ux=10m/s. But after some time steps, the Ux value become very small.
I think the velocity was not recycled at all. Anyone can help me ? The left figure is initial data, the right is some time steps later. |
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January 11, 2011, 09:24 |
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#51 |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Dear Jiang,
What is the boundary condition you are using? directMappedVelocityFlux, or directMapped(FixedValue)? Kind regards, Francois. |
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January 12, 2011, 04:44 |
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#52 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
Dear Fransje,
I am sorry, I haven't explain clearly. I run the case in the directory "tutorials/........./incompressible/les/pitzDirectMapped". I have tried 3 kinds of inflow conditions: 1. directMapped (nearestCell). 2. directMapped (nearestFace). 3. directMappedVelocityFlux (nearestFace). I use the solver "pisoFoam".The following is the detailed information. |
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January 12, 2011, 04:53 |
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#53 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
1. directMapped (nearestCell).
U file: boundaryField { inlet { type directMapped; setAverage false; average (10 0 0); value uniform (10 0 0); } boundary file: ( inlet { type directMappedPatch; nFaces 30; startFace 27238; sampleMode nearestCell; sampleRegion region0; samplePatch none; offset (0.05 0 0); } changeDictionaryDict file: dictionaryReplacement { boundary { inlet { type directMappedPatch; offset ( 0.05 0 0 ); sampleRegion region0; sampleMode nearestCell; samplePatch none; } } } the following is initial concours and 1000 time steps later |
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January 12, 2011, 05:00 |
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#54 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
2. directMapped (nearestFace).
U file: boundaryField { inlet { type directMapped; setAverage false; average (10 0 0); value uniform (10 0 0); } boundary file: inlet { type directMappedPatch; nFaces 30; startFace 27238; sampleMode nearestFace; sampleRegion region0; samplePatch none; offset (0.05 0 0); } changeDictionaryDict file: dictionaryReplacement { boundary { inlet { type directMappedPatch; offset ( 0.05 0 0 ); sampleRegion region0; sampleMode nearestFace; samplePatch none; } } } the following is initial concours and 1000 time steps later. |
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January 12, 2011, 05:07 |
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#55 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
3. directMappedVelocityFlux (nearestFace).
U file: boundaryField { inlet { type directMappedVelocityFlux; value uniform (10 0 0); phi phi; } boundary file: type directMappedPatch; nFaces 30; startFace 27238; sampleMode nearestFace; sampleRegion region0; samplePatch none; offset (0.05 0 0); } changeDictionaryDict file: dictionaryReplacement { boundary { inlet { type directMappedPatch; offset ( 0.05 0 0 ); sampleRegion region0; sampleMode nearestFace; samplePatch none; } } } the following is initial concours and 1000 time steps later. |
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January 12, 2011, 05:13 |
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#56 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
So I think the method "nearestCell" is correct, but the "nearestFace" method in new version 1.7.x is still wrong. I just updated to the version 1.7.x last month(2010.12.20).
Because only directMappedVelocityFlux can be used to modify to realise rescaling method, So the "nearestFace" is important for me. Could you give me some suggestions ? Thanks. |
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January 12, 2011, 09:43 |
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#57 |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Dear Jiang,
To be honest, I find surprising that you get any results at all with the settings you gave me.
Kind regards, Francois. |
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January 12, 2011, 10:35 |
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#58 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
And the nearestCell method shows correct result, but nearestFace method shows wrong result. I wait for nearestFace nearly 1 year. But it is a pity, I can't pass the example in my computer even using new version 1.7.x. How about your case ? could you give me some information about your case ? Thanks. |
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January 12, 2011, 11:17 |
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#59 |
Senior Member
Francois
Join Date: Jun 2010
Posts: 107
Rep Power: 21 |
Dear Jiang,
I definitely cannot reproduce your results using the method you described. As I understand it, you applied the following steps to get your results:
Kind regards, Francois. |
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January 12, 2011, 11:55 |
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#60 |
Senior Member
Jiang
Join Date: Oct 2009
Location: Japan
Posts: 186
Rep Power: 17 |
Dear Francois,
Yes, I did like this. Is there something which are not appropriate in my setting ? Thanks. |
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