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#21 |
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Hi All,
I am using fluent3DMeshToFoam to convert fully tetra *.msh file to OF_1.6. When I use polyDualMesh 80 to convert tetra to polyhedral, it increase my cell count for example from 65579 to 262316. Why this happen? It suppose to reduce my cell count. It happen to all my msh file regardless of how big the cell count is. Another question is, after I run meshCheck with my tetra mesh, it show my minimum face area and volume is extremely small. Why this happen? When I check in ANSA, the minumum length of my mesh is on 3mm. I attach the checkMesh output at below. Please help! Checking geometry... Overall domain bounding box (-0.02 -0.02 -0.02) (0.23 0.23 0.23) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (-5.55567e-18 1.43518e-17 1.8904e-17) OK. Max cell openness = 2.68989e-16 OK. Max aspect ratio = 5.5672 OK. Minumum face area = 2.35896e-06. Maximum face area = 0.000305596. Face area magnitudes OK. Min volume = 2.60873e-09. Max volume = 1.65414e-06. Total volume = 0.0155. Cell volumes OK. Mesh non-orthogonality Max: 58.5029 average: 15.0529 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.640031 OK. Rgds, airfoil |
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#22 | ||
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Bernhard Gschaider
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#23 |
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Hi Bernhard,
Thank you for replying. May I know what is the default unit length for fluent? What I did was, I mesh surface mesh using Ansa. Then I generate tetrahedral mesh with ANSA Tetra-FEM. Later I output the surface mesh and tetra to Fluent .msh ASCII. The *.msh contains surface mesh for boundary patch. When converting to OpenFOAM, I use fluent3DMeshToFoam *.msh -scale 0.001 because my mesh in ANSA is mm unit but dimensional unit for OpenFOAM is meter. That is why I use -scale 0.001. What is your opinion on this? Another question, why when I convert to polydualMesh, my cell count will increase? I view it using paraview and my polyhedral cell become finer as compare to tetras. Why is this happen? Rgds, Airfoil |
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#24 | |
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Bernhard Gschaider
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#25 |
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Hi Bernhard,
Thank you for the reply. I don't what is wrong with my mesh. Since then, I had abandon the desire to use fluent3DMeshToFoam. Now I am using ANSA 13 to output my delaunay mesh directly to OF then i do polyDualMesh 80 to convert tetrahedral to polyhedral. However there is an error when I do check mesh. Checking geometry... Overall domain bounding box (-5 -1 -0.194) (10 1 1.80605) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (8.54096e-18 8.41637e-18 -9.16634e-16) OK. Max cell openness = 2.84773e-16 OK. Max aspect ratio = 4.67014 OK. Minumum face area = 2.60311e-07. Maximum face area = 0.0145859. Face area magnitudes OK. Min volume = 3.41079e-09. Max volume = 0.00201841. Total volume = 59.8916. Cell volumes OK. Mesh non-orthogonality Max: 47.9936 average: 10.0362 Non-orthogonality check OK. ***Error in face pyramids: 362 faces are incorrectly oriented. <<Writing 362 faces with incorrect orientation to set wrongOrientedFaces Max skewness = 1.89527 OK. May I know what is wrongOrientedFaces mean? Rgds, Airfoil |
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#26 |
Senior Member
Vangelis Skaperdas
Join Date: Mar 2009
Location: Thessaloniki, Greece
Posts: 287
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Just a question.
Did you checkMesh the OpenFOAM mesh output from ANSA prior to poly conversion? |
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#27 |
New Member
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Hi Vangelis,
When I output the mesh from Ansa, it is in tetra. So there is no error when I do checkMesh. I noticed when I increase the split angle more then 90 deg, it will have no error but the edges is gone. From the other thread http://www.cfd-online.com/Forums/ope...eneration.html, Lillberg mentioned that the angle should be smaller then 90 deg and 45-80 is the best angle. This is true for STAR-CD as well. Please have a look on the attachment picture. The edge is gone for Poly_95.png. If I do polyDualmesh with 75 degree, the edge is kept but always have zero points error. Could some one please explain this? Appreciate! ![]() |
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#28 |
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Vangelis Skaperdas
Join Date: Mar 2009
Location: Thessaloniki, Greece
Posts: 287
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Hi airfoil,
I would expect that the required feature angle for the conversion should be lower, say 15 or 20 deg, in order to maintain the features of the model. Have you tried with such values? |
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#29 |
New Member
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Hi Vangelis,
I try to use 15 deg and there is error in face pyramid. I attach the checkMesh result below. lnx1762-014:ll13466> polyDualMesh 15 /*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 1.6-f802ff2d6c5a Exec : polyDualMesh 15 Date : Oct 13 2009 Time : 13:13:45 Host : lnx1762-014 PID : 1579 Case : /users/ll13466/training/openfoam/ahmed/35deg/ansa6 nProcs : 1 SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 // using new solver syntax: p { solver GAMG; preconditioner GAMG; tolerance 0.0001; relTol 0; smoother GaussSeidel; nPreSweeps 0; nPostSweeps 2; pFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 100; agglomerator faceAreaPair; mergeLevels 1; } // using new solver syntax: U { solver PBiCG; preconditioner DILU; tolerance 1e-06; relTol 0; } // using new solver syntax: k { solver PBiCG; preconditioner DILU; tolerance 1e-06; relTol 0; } // using new solver syntax: epsilon { solver PBiCG; preconditioner DILU; tolerance 1e-06; relTol 0; } // using new solver syntax: R { solver PBiCG; preconditioner DILU; tolerance 1e-06; relTol 0; } // using new solver syntax: nuTilda { solver PBiCG; preconditioner DILU; tolerance 1e-06; relTol 0; } Feature:15 minCos :0.965926 Dumping centres of featureFaces to obj file "featureFaces.obj" Dumping featureEdges to obj file "featureEdges.obj" Dumping featurePoints that become a single cell to obj file "singleCellFeaturePoints.obj" Dumping featurePoints that become multiple cells to obj file "multiCellFeaturePoints.obj" Reading volScalarField p Reading volScalarField k Reading volScalarField epsilon Reading volScalarField nuTilda Reading volVectorField U Reading volSymmTensorField R Writing dual mesh to 1 End [/users/ll13466/training/openfoam/ahmed/35deg/ansa6] [13:16] [13.Oct] lnx1762-014:ll13466> checkMesh /*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : 1.6-f802ff2d6c5a Exec : checkMesh Date : Oct 13 2009 Time : 13:17:16 Host : lnx1762-014 PID : 1610 Case : /users/ll13466/training/openfoam/ahmed/35deg/ansa6 nProcs : 1 SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 620905 faces: 7055740 internal faces: 6875276 cells: 3482754 boundary patches: 6 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 0 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 3482754 polyhedra: 0 Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface topology inlet 928 505 ok (non-closed singly connected) outlet 928 505 ok (non-closed singly connected) ground 37936 19141 ok (non-closed singly connected) ground_slip 1386 744 ok (non-closed singly connected) top_side 20726 10574 ok (non-closed singly connected) car 118560 59314 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (-5 -1 -0.194) (10 1 1.80605) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (9.31633e-18 1.03805e-17 1.11654e-15) OK. Max cell openness = 3.08056e-16 OK. Max aspect ratio = 7.61779 OK. Minumum face area = 3.482e-06. Maximum face area = 0.00930381. Face area magnitudes OK. Min volume = 2.63917e-09. Max volume = 0.000275506. Total volume = 59.8916. Cell volumes OK. Mesh non-orthogonality Max: 60.8783 average: 14.6742 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.802059 OK. Mesh OK. Time = 1 Mesh stats points: 3677823 faces: 4297096 internal faces: 4193893 cells: 620905 boundary patches: 6 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 0 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 620905 Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface topology inlet 661 1244 ok (non-closed singly connected) outlet 661 1244 ok (non-closed singly connected) ground 19854 39353 ok (non-closed singly connected) ground_slip 940 1782 ok (non-closed singly connected) top_side 12904 24192 ok (non-closed singly connected) car 68183 128361 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (-5 -1 -0.194) (10 1 1.80605) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (1.57636e-17 7.8324e-18 1.4391e-15) OK. Max cell openness = 2.53783e-16 OK. Max aspect ratio = 4.59728 OK. Minumum face area = 5.31351e-07. Maximum face area = 0.0141903. Face area magnitudes OK. Min volume = 9.34748e-09. Max volume = 0.00192506. Total volume = 59.8916. Cell volumes OK. Mesh non-orthogonality Max: 47.3134 average: 9.77624 Non-orthogonality check OK. ***Error in face pyramids: 182 faces are incorrectly oriented. <<Writing 182 faces with incorrect orientation to set wrongOrientedFaces Max skewness = 1.65935 OK. Failed 1 mesh checks. End There is no problem with my tetras. I am using Ansa to generate Delaunay tetra which is the must for polyDualMesh. Have a look on the picture. It maintained the edges very well and split into small mesh at the edge. Anything else I can do? |
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#30 |
Senior Member
Vangelis Skaperdas
Join Date: Mar 2009
Location: Thessaloniki, Greece
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Sorry airfoil,
I cannot think of anything, apart from trying to run the solver regardless of the errors in checkMesh Could you at least visualize the set wrongOrientedFaces? |
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#31 |
New Member
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Vengelis,
Sorry. How to view the problem faces in paraview? The error set is as below. /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 1.6 | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class faceSet; location "constant/polyMesh/sets"; object wrongOrientedFaces; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // 182 ( 4260149 4260150 4260151 4261475 4261476 4261479 4261480 4262839 4262840 4262841 4263087 4263088 4263089 4263166 4263167 4263168 4263432 4263433 4263434 4264256 4264257 4264258 4264638 4264639 4264643 4265533 4265534 4265535 4266285 4266286 4266287 4267482 4267486 4267487 4269089 4269090 4269091 4269176 4269177 4269178 4270103 4270104 4270105 4270179 4270180 4271025 4271026 4271030 4273857 4273858 4273859 4274338 4274342 4274343 4276672 4276673 4276674 4276937 4276938 4276939 4277862 4277863 4277864 4278247 4278248 4278249 4279102 4279103 4279104 4279173 4279174 4279175 4279202 4279206 4279207 4279643 4279644 4279648 4279651 4279652 4279656 4283956 4283957 4283958 4287369 4287370 4287371 4289046 4289047 4289048 4289049 4291614 4291615 4291619 4228997 4228998 4228999 4231308 4231309 4231310 4298022 4298023 4298024 4233074 4233075 4233076 4233133 4233134 4233135 4233210 4233211 4233212 4233930 4233931 4233932 4234168 4234169 4234170 4235677 4235678 4235679 4235925 4235929 4235930 4235971 4235972 4235973 4237542 4237543 4237544 4237676 4237677 4237678 4237679 4237997 4237998 4237999 4238234 4238235 4238236 4238241 4238242 4238243 4238716 4238717 4238718 4239406 4239410 4239411 4241399 4241400 4241401 4242815 4242816 4242817 4243471 4243472 4243473 4245487 4245488 4245489 4245490 4245494 4245495 4252018 4252019 4252020 4256099 4256103 4256104 4256506 4256507 4256508 4257825 4257826 4257827 4258162 4258163 4258164 4258270 4258271 4258275 ) // ************************************************** *********************** // |
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#32 | |
Assistant Moderator
Bernhard Gschaider
Join Date: Mar 2009
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Quote:
How to: In paraFoam check "Include Sets" then check the set in question in the list (where the patches are). Afterwards select the set in the "Extract Block"-filter |
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#33 |
New Member
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Bernhard,
Thank you for the guide. There are problem with the mesh when viewing in Paraview. Does OF have any utility which I can fix the mesh manually? |
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#34 |
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Cá Mon 9
Join Date: Nov 2011
Location: Huế
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Hi all!
I don't know extracly your mesh is 3D or 2D but if Your mesh is 3D I don't see how many cell it is. I have same problem when convert a cube in Gambit to OpenFoam - But don't see the number of cell created - althought Face and Point are good. Who can give me some advice !!!! |
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#35 |
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Maxime Perelli
Join Date: Mar 2009
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use checkMesh utility
__________________
In memory of my friend Hervé: CFD engineer & freerider ![]() |
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#36 |
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Cá Mon 9
Join Date: Nov 2011
Location: Huế
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![]() This is my cellzone file - it has only information which isn't like cell file in example ... Can you explain meaning of this file for me ??? I tranformed it from Gambit to OpenFoam Mesh - it's my result file cellzone |
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#37 |
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Read the header of constant/polymesh/owner file.
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#38 |
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Cá Mon 9
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Location: Huế
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Thank you very much
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#39 |
New Member
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Your cell number is 125
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#40 |
Member
张德胜
Join Date: Oct 2011
Posts: 71
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I now face the same trouble with the fluent3dmeshtofoam,i get the .cas format file,when i execute fluent3dmeshtofoam,i get the error:--> FOAM FATAL ERROR:
Do not understand characters: / on line 157058 From function fluentMeshToFoam::lexer in file fluent3DMeshToFoam.L at line 747. FOAM exiting Can you help me if you are free? |
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