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[Other] "did not succesfully snap mesh. Giving up" |
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July 8, 2013, 13:17 |
"did not succesfully snap mesh. Giving up"
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#1 |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
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Hi Dear All;
i use snappyHexMesh for meshing the domain around two element airfoil. during the running of snappyHexMesh, this message is appear that ""did not succesfully snap mesh. Giving up"" . is it related to the parameters in snapControls section of snappyHexMeshDict? if yes, what changes should i do in my snappyHexMeshDict that i have attached in the following? thank you |
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July 8, 2013, 15:00 |
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#2 |
Senior Member
Daniel P. Combest
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Location: St. Louis, USA
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I would make your base mesh smaller (i.e. change your blockMeshDict to have more subdivisions), decrease your levels on your edges from 6 7 to 5 6 or lower depending on your base mesh sizing and change
Code:
tolerance 1.0; nSolveIter 300; Last edited by chegdan; July 8, 2013 at 15:55. Reason: i noticed you were actually using 2.2.x |
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July 9, 2013, 02:28 |
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#3 | |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
Posts: 229
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Quote:
i am using the OF 2.2.0. this is my blockMeshDict, would you please look at it and tell me is it necessary to increase the subdivisions? |
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July 9, 2013, 10:39 |
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#4 |
Senior Member
Daniel P. Combest
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Location: St. Louis, USA
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The closer you make your base mesh cell aspect ratio to unity (equal length in x y and z direction), the better results you will see in SHM. Try:
Code:
blocks ( hex (0 1 2 3 4 5 6 7) (880 480 1) simpleGrading (1 1 1) ); |
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July 9, 2013, 11:47 |
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#5 | |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
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Rep Power: 14 |
Quote:
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July 9, 2013, 11:50 |
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#6 | |
Senior Member
Daniel P. Combest
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Location: St. Louis, USA
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Quote:
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July 9, 2013, 12:07 |
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#7 | |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
Posts: 229
Rep Power: 14 |
Quote:
is this cell size belong to all the cells around my airfoil? i ask this question, becuase for computing the y+ i only need to know the first cell size of my mesh. thank you again for your advice |
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July 9, 2013, 12:14 |
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#8 |
Senior Member
Daniel P. Combest
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Location: St. Louis, USA
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From my experience
lunderSharmaKE needs y+ <= 1 but it really can't be calculated until your simulation has been run to know how much further you need to refine your mesh. You can use the yPlusRAS utility to calculate the y+ value. |
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July 9, 2013, 12:37 |
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#9 | |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
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Quote:
is it better to use level (6 6) for the refinementSurface, to have squre cells size? |
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July 9, 2013, 13:02 |
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#10 |
Senior Member
Daniel P. Combest
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the (6 6) would mean that if a featureEdge is encountered then the same refinement (a level 6) will be used. If you had done a (6 7) then a further refinement of 7 would be done around the "turn" of the edge.
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July 9, 2013, 13:20 |
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#11 |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
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Thank you i am running the case, with new blockMeshDict and also new snappyHexMeshDict. i'll put the resulted logFile after fininshing.
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July 10, 2013, 08:08 |
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#12 |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
Posts: 229
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Hi,
i didn't recive that message anymore, thank you very much for your kind help. i put some picture of my mesh, would you please tell me is this mesh looks good? and i also attach the snappyHexMesh and checkMesh logfile. as you see in checkMesh, "Mesh non-orthogonality Max: 59.5431 average: 7.46241" is it fine? thank you very much again |
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July 10, 2013, 08:15 |
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#13 |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
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and these are, another picture of this snappyHexMesh, as you see ot just doesn't capture the main trailling edge corner angle true,if you have a comment to fix it, please tell me
thanks. |
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July 10, 2013, 12:38 |
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#14 | |
Senior Member
Daniel P. Combest
Join Date: Mar 2009
Location: St. Louis, USA
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Quote:
also...if you are doing a 2D case, you will be better off doing a 2D mesh. have a look at Code:
tutorials/incompressible/pimpleDyMFoam/wingMotion/wingMotion_snappyHexMesh For resolving the edge, you could try drawing a refinement box around the edge and then make the cells there really small. Lastly, to make your mesh look better in screenshots (i.e. get rid of diagonal cuts in hex cells) you can check "use VTKPolyhedron" in Paraview object inspector when you first import results into Paraview. |
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July 10, 2013, 13:17 |
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#15 | |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
Posts: 229
Rep Power: 14 |
Quote:
i have another problem yet as you see, the mesh around the airfoil is extremely tiny but, i get the pressure countour around it really bad. i write my problem in the solving forum of openFoam. Home > Forums > OpenFOAM Running, Solving & CFD > wrong contour of pressure at the airfoil leading edge would you please take a look at it,thank you. |
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July 10, 2013, 13:33 |
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#16 |
Senior Member
Daniel P. Combest
Join Date: Mar 2009
Location: St. Louis, USA
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I will leave that thread to the experts. However, you may want to add some boundary layers cells to your mesh and/or increase the refinement near the surface. If you give as much info as possible on that thread and also search the forum....i bet you will get it solved. Good luck!
Last edited by chegdan; July 14, 2013 at 13:58. |
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July 10, 2013, 13:47 |
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#17 | |
Senior Member
saeideh mohamadi
Join Date: Aug 2012
Posts: 229
Rep Power: 14 |
Quote:
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