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[snappyHexMesh] upper and lower patch for a 0_thick Membrane in a wind tunnel |
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November 12, 2012, 18:06 |
upper and lower patch for a 0_thick Membrane in a wind tunnel
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#1 |
Member
Join Date: Jul 2012
Posts: 66
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Hello All!
I have a membrane that I need to simulate wind pressure on.. I have it in an STL file (a zero thickness surface) I am trying to get 2 patches for the membrane: one for the upper side and one for the lower side. I did the following: 1-blockMesh with extra patches Umb1 and Umb2 Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.0.1 | | \\ / A nd | Web: http://www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object blockMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // convertToMeters 1; vertices ( (-100 -100 0)//0 (-100 100 0)//1 (-100 100 75)//2 (-100 -100 75)//3 (200 -100 0)//4 (200 100 0)//5 (200 100 75)//6 (200 -100 75)//7 ); blocks ( hex (0 1 2 3 4 5 6 7) (50 20 75) simpleGrading (1 1 1) ); edges ( ); boundary ( inlet { type patch; faces ( (0 3 2 1) ); } outlet { type patch; faces ( (4 7 6 5) ); } bottomWall { type wall; faces ( (0 1 5 4) ); } topWall { type wall; faces ( (3 2 6 7) ); } frontAndBack { type symmetryPlane; faces ( (0 4 7 3) (1 5 6 2) ); } Umb1 { type patch; faces ( ); } Umb2 { type patch; faces ( ); } ); mergePatchPairs ( ); // ************************************************************************* // 3- createBaffles Umb '(Umb1 Umb2)' I got 2 patches .. but they are not the upper and the lower side of the Umbrella ... I knew that when I tried to simulate and got crazy results for the pressure (See attachments) The Pressure should be consistant on each side; i.e. either positive or negative in a continuos manner ... the pic shows that each patch Umb1 and Umb2 is a random combination of the upper and the lower side of the Umbrella I will gratefully appreciate any suggestion! Thanks! Last edited by hfs; November 12, 2012 at 19:18. |
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November 13, 2012, 11:53 |
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#2 |
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Join Date: Jul 2012
Posts: 66
Rep Power: 14 |
Does that have something to do with the orientation of the faces?
If yes, how can I control the orientation of my faces ... and then how can I make 2 patched depending on the orientation so that I insure that Umb1 is Upper and Umb2 is Lower? |
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November 13, 2012, 12:29 |
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#3 |
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Join Date: Jul 2012
Posts: 66
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Here I have uploaded my Meshing Case and Simulation Case
http://dl.dropbox.com/u/32336583/How...Patches.tar.gz Please take a look Thanks! Last edited by hfs; November 13, 2012 at 13:05. |
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November 18, 2012, 20:10 |
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#4 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
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Greetings hfs,
I learned a new trick today using your case! We can use STL surfaces for creating internal "faceZones" only, without the need for creating "cellZones"! I didn't know that worked! This means that we can try and model mesh with snappyHexMesh, at least in an attempt to force certain faces to be along a ghostly geometry So I did some testing and:
Best regards, Bruno
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November 18, 2012, 20:33 |
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#5 |
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Join Date: Jul 2012
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Thank you very much for your tries and detailed answer
really appreciate it. I will try your solution with 2 snapping phases .. Thanks again! Kind Regards, |
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October 15, 2013, 01:50 |
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#6 |
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Ripudaman Manchanda
Join Date: May 2013
Posts: 55
Rep Power: 13 |
Has anyone been able to find a better solution to this problem? Is using two phases of SHM the only way to fix this?
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October 15, 2013, 17:26 |
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#7 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,981
Blog Entries: 45
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Greetings Ripudaman,
OpenFOAM 2.2 is able to snap to patches, but it's still not perfect: http://www.openfoam.org/mantisbt/view.php?id=1038 And it should be able to create baffles, using a similar strategy. I think there is one or two tutorials in OpenFOAM 2.2 that use snappyHexMesh to create baffles... Best regards, Bruno
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October 15, 2013, 17:41 |
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#8 |
Member
Ripudaman Manchanda
Join Date: May 2013
Posts: 55
Rep Power: 13 |
Thank you for your reply Bruno. I will explore your citation further.
I have been able to create planar baffles using SHM and use them as boundaries (internal) and applied different stresses on the faces to create fractures. I am now trying to do the same thing for curved fractures. Best, Ripu |
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