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April 13, 2015, 10:04 |
engineFoam: unstable velocity field
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#1 |
New Member
Max M.
Join Date: Sep 2014
Posts: 5
Rep Power: 12 |
Hello Foamers,
I'm trying to simulate combustion in a diesel engine, by copying our Kiva mesh to the combustion/engineFoam/kivaTest tutorial case. Our mesh does not contain the whole 360° cylinder, but a "piece of cake" with cyclic boundary. Mesh conversion runs just fine, but engineFoam can only compute crank angles from -180° to at most -178° before the velocity field at the center of the piston is getting very unstable and finally janafThermo gives the Fatal Error. Maybe just copying a cyclic mesh to the (non-cyclic) Tutorial Case isn't enough. Can anyone help me? Thanks in advance, Max Last edited by mmeyer; April 14, 2015 at 04:07. Reason: changing the title, because the main issue has changed |
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April 14, 2015, 02:56 |
Log Files
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#2 |
New Member
Max M.
Join Date: Sep 2014
Posts: 5
Rep Power: 12 |
I am using Foam-Extend-3.1
These are my logfiles including an attempt to refine the mesh. |
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April 14, 2015, 04:02 |
Update
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#3 |
New Member
Max M.
Join Date: Sep 2014
Posts: 5
Rep Power: 12 |
I edited the global controlDict in the following way:
Code:
... DebugSwitches { cyclic 1; ... } ... Tolerances { patchFaceMatchTol 1e-3; ... } ... Code:
cyclicPolyPatch::calcTransforms : Writing half0 faces to file "/home/mmeyer/foam/mmeyer-3.1/run/KIVAgrid/kivaTest/VTK/cyclic_half0_faces" cyclicPolyPatch::calcTransforms : Writing half1 faces to file "/home/mmeyer/foam/mmeyer-3.1/run/KIVAgrid/kivaTest/VTK/cyclic_half1_faces" Unknown transform: calculating transform from geometry --> FOAM Serious Error : From function void cyclicPolyPatch::calcTransforms() const in file meshes/polyMesh/polyPatches/constraint/cyclic/cyclicPolyPatch.C at line 246 Transformation tensor is not constant for the cyclic patch cyclic. Please reconsider your setup and definition of cyclic boundaries. cyclicPolyPatch::calcTransforms : Writing transform_half0 faces to file "/home/mmeyer/foam/mmeyer-3.1/run/KIVAgrid/kivaTest/VTK/cyclic_transform_half0_faces" |
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April 14, 2015, 05:05 |
How can I define the missing Transformation Tensor?
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#4 |
New Member
Max M.
Join Date: Sep 2014
Posts: 5
Rep Power: 12 |
My latest approach is to define the unknown transformation tensor by hand, but I don't know if the faceSets are created and named properly by the kivaToFoam tool.
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May 8, 2015, 07:51 |
Problem with cyclic boundary on engine sector mesh
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#5 |
Member
Tomislav Sencic
Join Date: Mar 2009
Posts: 42
Rep Power: 17 |
I am trying to simulate a diesel engine using a sector of 51 degree mesh.
I use the foam-extend-3.1 version. The mesh is created with blockMesh. I obtain the error --> FOAM FATAL ERROR: face 2 area does not match neighbour 5 by 179.301% -- possible face ordering problem. patch:front my area:155.763 neighbour area:2854.34 matching tolerance:0.0001 Mesh face:19 vertices:4((15.4535 -7.43725 -13.65) (22.0764 -10.6246 -19.5) (28.2262 -13.5844 0) (19.7584 -9.50906 0)) Neighbour face:22 vertices:4((28.2262 -13.5844 0) (48.6582 -23.4176 0) (48.6582 -23.4176 125.88) (28.2262 -13.5844 125.88)) Other errors also exist, only the largest is reported. Please rerun with cyclic debug flag set for more information. This is my blockMeshDict file: /*--------------------------------------------------------------------------* | ========= | | | \ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \ / O peration | Version: 1.0 | | \ / A nd | Web: http://www.openfoam.org | | \/ M anipulation | | *---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; root ; case ; instance ; local ; class dictionary; object blockMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // convertToMeters 0.001; vertices ( (0.973163 -0.468352 -17.8) //0 (22.0764 -10.6246 -19.5) //1 (22.0764 10.6246 -19.5) //2 (0.973163 0.468352 -17.8) //3 (0.973163 -0.468352 0) //4 (28.2262 -13.5844 0) //5 (48.6582 -23.4176 0) //6 (48.6582 23.4176 0) //7 (28.2262 13.5844 0) //8 (0.973163 0.468352 0) //9 (0.973163 -0.468352 125.88) //10 (28.2262 -13.5844 125.88) //11 (48.6582 -23.4176 125.88) //12 (48.6582 23.4176 125.88) //13 (28.2262 13.5844 125.88) //14 (0.973163 0.468352 125.88) //15 (15.4535 -7.43725 -13.65) //16 (15.4535 7.43725 -13.65) //17 (19.7584 -9.50906 0) //18 (19.7584 9.50906 0) //19 (19.7584 -9.50906 125.88) //20 (19.7584 9.50906 125.88) //21 (0.973163 -0.468352 -8.9) //22 (0.973163 0.468352 -8.9) //23 ); blocks ( hex (0 1 2 3 22 16 17 23) (10 25 6) simpleGrading (1 1 1) hex (22 16 17 23 4 18 19 9) (10 25 14) simpleGrading (1 1 1) hex (16 1 2 17 18 5 8 19) (6 25 14) simpleGrading (1 1 1) hex (4 18 19 9 10 20 21 15) (10 25 26) simpleGrading (1 1 1) hex (18 5 8 19 20 11 14 21) (6 25 26) simpleGrading (1 1 1) hex (5 6 7 8 11 12 13 14) (16 25 26) simpleGrading (1 1 1) ); edges ( arc 0 3 (1.08 0 -17.8) arc 1 2 (24.5 0 -19.5) arc 4 9 (1.08 0 0) arc 5 8 (31.325 0 0) arc 6 7 (54 0 0) arc 10 15 (1.08 0 125.88) arc 11 14 (31.325 0 125.88) arc 12 13 (54 0 125.88) arc 22 23 (1.08 0 -8.9) arc 16 17 (17.15 0 -13.65) arc 18 19 (21.9275 0 0) arc 20 21 (21.9275 0 125.88) spline 0 1( (4.50539 -2.1683 -19) (9.01077 -4.33659 -20) (16.2194 -7.80586 -21) ) spline 3 2( (4.50539 2.1683 -19) (9.01077 4.33659 -20) (16.2194 7.80586 -21) ) spline 1 5( (28.2262 -13.5844 -11) ) spline 2 8( (28.2262 13.5844 -11) ) ); patches ( wall piston ( ( 0 1 2 3) ( 1 2 8 5) (5 6 7 8) ) wall liner ( ( 6 12 13 7) ) wall cylinderHead ( ( 10 20 21 15) ( 20 11 14 21) ( 11 12 13 14) ) symmetryPlane symmetryFaces ( ( 0 22 23 3) ( 22 4 9 23) ( 4 10 15 9) ) cyclic front ( ( 0 1 16 22) ( 22 16 18 4) ( 16 1 5 18 ) ( 4 18 20 10) ( 18 5 11 20) ( 5 6 12 11) ) cyclic back ( ( 3 23 17 2) ( 23 9 19 17) ( 17 19 8 2) ( 9 15 21 19) ( 19 21 14 8) ( 8 14 13 7) ) ); mergePatchPairs (); // ************************************************** *********************** // I also tried to have one cyclic boundary, frontAndBack, then I get: --> FOAM Serious Error : From function void cyclicPolyPatch::calcTransforms() const in file meshes/polyMesh/polyPatches/constraint/cyclic/cyclicPolyPatch.C at line 246 Transformation tensor is not constant for the cyclic patch frontAndBack. Please reconsider your setup and definition of cyclic boundaries. I remember that I used this kind of mesh on earlier OF versions, like OF-1.4 and 1.5. It should be a simple thing, this is not a complex geometry and is similar for many engine applications, but I see many have problems with cyclics :-( How could I solve the problem? |
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May 11, 2015, 06:49 |
check your transformation tensor
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#6 | |
New Member
Max M.
Join Date: Sep 2014
Posts: 5
Rep Power: 12 |
Quote:
Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | foam-extend: Open Source CFD | | \\ / O peration | Version: 3.1 | | \\ / A nd | Web: http://www.extend-project.de | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class polyBoundaryMesh; location "constant/polyMesh"; object boundary; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 4 ( piston { type wall; nFaces 2140; startFace 165197; } liner { type wall; nFaces 460; startFace 167337; } cylinderHead { type wall; nFaces 1700; startFace 167797; } cyclic { type cyclic; nFaces 5686; startFace 169497; featureCos 0.9; transform rotational; rotationAxis (0 0 1); rotationCentre (0 0 0); rotationAngle 308.571; } ) // ************************************************************************* // |
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May 22, 2015, 05:05 |
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#7 |
Member
Tomislav Sencic
Join Date: Mar 2009
Posts: 42
Rep Power: 17 |
Thank You very much. It's working now.
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August 11, 2017, 00:27 |
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#8 |
New Member
Qiyan Zhou
Join Date: Sep 2016
Posts: 16
Rep Power: 10 |
Hi mmeyer
I am facing the same problem now... When using a sector for simulation, the velocity in the center of piston is unstable. Have you got the solutions or any tips? I am really confused by that Thanks in advance Sent from my iPhone using CFD Online Forum mobile app |
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August 11, 2017, 08:55 |
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#9 |
New Member
Qiyan Zhou
Join Date: Sep 2016
Posts: 16
Rep Power: 10 |
my simulation runs fine from -180--146,and then the velocity becomes really high and then janafThermo out of range
Any advice is welcome Thanks in advance Sent from my iPhone using CFD Online Forum mobile app |
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Tags |
cyclic boundary, enginefoam, kivatofoam |
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