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[snappyHexMesh] Igloo tutorial: Mesh doesn't follow edges |
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October 5, 2012, 04:55 |
Igloo tutorial: Mesh doesn't follow edges
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#1 |
Super Moderator
Maxime Perelli
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Hello,
I am trying to start with snappyHexMesh, especially with igloo tutorial Tutorial is successfull, and I wanted to do exactly the same stuff, BUT from an CAD import. So I designed exactly the same geometry, and I exported it in STL Then I generate the *.eMesh file with surfaceFeaturConvert BlockMesh snappyHexMesh Everything is ok, since I checked the result in Paraview I don't succeed to have aligned Mesh on edge. I don't understand, because I have exactly the same blockMesh and snayppyHexMesh files, and I just adapted the last one (geometry) geometry { igloo.stl { type triSurfaceMesh; name igloo; tolerance 1e-5; maxTreeDepth 10; regions { igloo; } } }; Any idea? Sans titre.jpg
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October 5, 2012, 07:38 |
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#2 |
Senior Member
Eloïse
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Hi!
Is your STL a sphere or a half-sphere? Which version of OF do you use? Regards, Eloïse |
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October 5, 2012, 07:40 |
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#3 |
Super Moderator
Maxime Perelli
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hello,
geometry is exactly he same than the one in the tutorial: so this is a half-sphere OF2.0.1
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October 5, 2012, 07:46 |
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#4 |
Senior Member
Eloïse
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OF2.0 has a bug related to circular feature edges. For some reason, it does not snap to them. See the details about it on this post:
http://www.cfd-online.com/Forums/ope...ain-edges.html It has been solved for OF2.1 so if you can, I'd recommend you to upgrade to that version. Regards, Eloïse |
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October 5, 2012, 09:57 |
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#5 |
Super Moderator
Maxime Perelli
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ok I am trying to install OF2.1.1.
But I have a pre-installed version of OF (caelinux) and sourcing gives me troubles... So I will continue on Monday and will give you feedback
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October 5, 2012, 10:21 |
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#6 | |
Retired Super Moderator
Bruno Santos
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Greetings to all!
Quote:
Code:
wmUNSET #or source $WM_PROJECT_DIR/etc/config/unset.sh Best regards, Bruno
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October 8, 2012, 02:50 |
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#7 |
Super Moderator
Maxime Perelli
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ok, I installed OF2.1.1
But the issue remains On the picture I draw also the edged from surfaceFeatureConvert *.eMesh (in red) Again, I only changed lines in geometry and I updated name everywhere geometry { igloo.stl { type triSurfaceMesh; name igloo; tolerance 1e-5; maxTreeDepth 10; regions { igloo; } } }; Sans titre.png
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In memory of my friend Hervé: CFD engineer & freerider |
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October 8, 2012, 03:53 |
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#8 |
Senior Member
Eloïse
Join Date: Jul 2012
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Hi Max,
Can you post your entire snappyHexMeshDict? Regards, Eloïse |
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October 8, 2012, 04:02 |
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#9 |
Super Moderator
Maxime Perelli
Join Date: Mar 2009
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/*--------------------------------*- C++ -*----------------------------------*\
| ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.0.1 | | \\ / A nd | Web: www.OpenFOAM.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object snappyHexMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // // Which of the steps to run castellatedMesh true; snap true; addLayers true; // Geometry. Definition of all surfaces. All surfaces are of class // searchableSurface. // Surfaces are used // - to specify refinement for any mesh cell intersecting it // - to specify refinement for any mesh cell inside/outside/near // - to 'snap' the mesh boundary to the surface geometry { igloo.stl { type triSurfaceMesh; name igloo; tolerance 1e-5; maxTreeDepth 10; regions { igloo; } } }; // Settings for the castellatedMesh generation. castellatedMeshControls { // Refinement parameters // ~~~~~~~~~~~~~~~~~~~~~ // If local number of cells is >= maxLocalCells on any processor // switches from from refinement followed by balancing // (current method) to (weighted) balancing before refinement. maxLocalCells 1000000; // Overall cell limit (approximately). Refinement will stop immediately // upon reaching this number so a refinement level might not complete. // Note that this is the number of cells before removing the part which // is not 'visible' from the keepPoint. The final number of cells might // actually be a lot less. maxGlobalCells 2000000; // The surface refinement loop might spend lots of iterations refining just a // few cells. This setting will cause refinement to stop if <= minimumRefine // are selected for refinement. Note: it will at least do one iteration // (unless the number of cells to refine is 0) minRefinementCells 100; // Number of buffer layers between different levels. // 1 means normal 2:1 refinement restriction, larger means slower // refinement. nCellsBetweenLevels 1; // Explicit feature edge refinement // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // Specifies a level for any cell intersected by its edges. // This is a featureEdgeMesh, read from constant/triSurface for now. features ( { file "igloo.eMesh"; level 3; } ); // Surface based refinement // ~~~~~~~~~~~~~~~~~~~~~~~~ // Specifies two levels for every surface. The first is the minimum level, // every cell intersecting a surface gets refined up to the minimum level. // The second level is the maximum level. Cells that 'see' multiple // intersections where the intersections make an // angle > resolveFeatureAngle get refined up to the maximum level. refinementSurfaces { igloo { // Surface-wise min and max refinement level level (2 2); regions { // Region-wise override igloo { level (1 1); } } } } // Resolve sharp angles on fridges resolveFeatureAngle 60; // Region-wise refinement // ~~~~~~~~~~~~~~~~~~~~~~ // Specifies refinement level for cells in relation to a surface. One of // three modes // - distance. 'levels' specifies per distance to the surface the // wanted refinement level. The distances need to be specified in // descending order. // - inside. 'levels' is only one entry and only the level is used. All // cells inside the surface get refined up to the level. The surface // needs to be closed for this to be possible. // - outside. Same but cells outside. refinementRegions { } // Mesh selection // ~~~~~~~~~~~~~~ // After refinement patches get added for all refinementSurfaces and // all cells intersecting the surfaces get put into these patches. The // section reachable from the locationInMesh is kept. // NOTE: This point should never be on a face, always inside a cell, even // after refinement. locationInMesh (3 0.28 0.43); // Whether any faceZones (as specified in the refinementSurfaces) // are only on the boundary of corresponding cellZones or also allow // free-standing zone faces. Not used if there are no faceZones. allowFreeStandingZoneFaces true; } // Settings for the snapping. snapControls { //- Number of patch smoothing iterations before finding correspondence // to surface nSmoothPatch 3; //- Relative distance for points to be attracted by surface feature point // or edge. True distance is this factor times local // maximum edge length. tolerance 4.0; //- Number of mesh displacement relaxation iterations. nSolveIter 30; //- Maximum number of snapping relaxation iterations. Should stop // before upon reaching a correct mesh. nRelaxIter 5; } // Settings for the layer addition. addLayersControls { // Are the thickness parameters below relative to the undistorted // size of the refined cell outside layer (true) or absolute sizes (false). relativeSizes true; // Per final patch (so not geometry!) the layer information layers { igloo { nSurfaceLayers 1; } } // Expansion factor for layer mesh expansionRatio 1.0; //- Wanted thickness of final added cell layer. If multiple layers // is the // thickness of the layer furthest away from the wall. // Relative to undistorted size of cell outside layer. // is the thickness of the layer furthest away from the wall. // See relativeSizes parameter. finalLayerThickness 0.5; //- Minimum thickness of cell layer. If for any reason layer // cannot be above minThickness do not add layer. // Relative to undistorted size of cell outside layer. // See relativeSizes parameter. minThickness 0.25; //- If points get not extruded do nGrow layers of connected faces that are // also not grown. This helps convergence of the layer addition process // close to features. // Note: changed(corrected) w.r.t 17x! (didn't do anything in 17x) nGrow 0; // Advanced settings //- When not to extrude surface. 0 is flat surface, 90 is when two faces // make straight angle. featureAngle 60; //- Maximum number of snapping relaxation iterations. Should stop // before upon reaching a correct mesh. nRelaxIter 5; // Number of smoothing iterations of surface normals nSmoothSurfaceNormals 1; // Number of smoothing iterations of interior mesh movement direction nSmoothNormals 3; // Smooth layer thickness over surface patches nSmoothThickness 10; // Stop layer growth on highly warped cells maxFaceThicknessRatio 0.5; // Reduce layer growth where ratio thickness to medial // distance is large maxThicknessToMedialRatio 0.3; // Angle used to pick up medial axis points // Note: changed(corrected) w.r.t 16x! 90 degrees corresponds to 130 in 16x. minMedianAxisAngle 90; // Create buffer region for new layer terminations nBufferCellsNoExtrude 0; // Overall max number of layer addition iterations. The mesher will exit // if it reaches this number of iterations; possibly with an illegal // mesh. nLayerIter 50; } // Generic mesh quality settings. At any undoable phase these determine // where to undo. meshQualityControls { //- Maximum non-orthogonality allowed. Set to 180 to disable. maxNonOrtho 65; //- Max skewness allowed. Set to <0 to disable. maxBoundarySkewness 20; maxInternalSkewness 4; //- Max concaveness allowed. Is angle (in degrees) below which concavity // is allowed. 0 is straight face, <0 would be convex face. // Set to 180 to disable. maxConcave 80; //- Minimum pyramid volume. Is absolute volume of cell pyramid. // Set to a sensible fraction of the smallest cell volume expected. // Set to very negative number (e.g. -1E30) to disable. minVol 1e-13; //- Minimum quality of the tet formed by the face-centre // and variable base point minimum decomposition triangles and // the cell centre. Set to very negative number (e.g. -1E30) to // disable. // <0 = inside out tet, // 0 = flat tet // 1 = regular tet minTetQuality 1e-30; //- Minimum face area. Set to <0 to disable. minArea -1; //- Minimum face twist. Set to <-1 to disable. dot product of face normal //- and face centre triangles normal minTwist 0.05; //- minimum normalised cell determinant //- 1 = hex, <= 0 = folded or flattened illegal cell minDeterminant 0.001; //- minFaceWeight (0 -> 0.5) minFaceWeight 0.05; //- minVolRatio (0 -> 1) minVolRatio 0.01; //must be >0 for Fluent compatibility minTriangleTwist -1; // Advanced //- Number of error distribution iterations nSmoothScale 4; //- amount to scale back displacement at error points errorReduction 0.75; } // Advanced // Flags for optional output // 0 : only write final meshes // 1 : write intermediate meshes // 2 : write volScalarField with cellLevel for postprocessing // 4 : write current intersections as .obj files debug 0; // Merge tolerance. Is fraction of overall bounding box of initial mesh. // Note: the write tolerance needs to be higher than this. mergeTolerance 1e-6; // ************************************************** *********************** //
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In memory of my friend Hervé: CFD engineer & freerider |
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October 8, 2012, 09:21 |
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#10 |
Senior Member
Eloïse
Join Date: Jul 2012
Location: Trondheim, Norway
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I'm sorry but I can't figure out what's wrong... I'm actually not using V2.1 myself yet so I can't test your snappyHexMeshDict, but I taught it would do the trick!
Maybe someone else has an idea? Regards, Eloïse |
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October 8, 2012, 09:30 |
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#11 |
Super Moderator
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41 |
Ok thanks anyway
I post the blockMesh File, and I also attach the stl file (form igloo geometry) if it can help igloo.zip /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2.0.1 | | \\ / A nd | Web: www.OpenFOAM.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object blockMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // convertToMeters 1; vertices ( (-2.03 -2.0 0) ( 8.03 -2.0 0) ( 8.03 8.0 0) (-2.03 8.0 0) (-2.03 -2.0 5) ( 8.03 -2.0 5) ( 8.03 8.0 5) (-2.03 8.0 5) ); blocks ( hex (0 1 2 3 4 5 6 7) (20 20 20) simpleGrading (1 1 1) ); edges ( ); boundary ( maxY { type empty; faces ( (3 7 6 2) ); } minX { type empty; faces ( (0 4 7 3) ); } maxX { type empty; faces ( (2 6 5 1) ); } minY { type empty; faces ( (1 5 4 0) ); } ground { type wall; faces ( (0 3 2 1) ); } maxZ { type empty; faces ( (4 5 6 7) ); } ); mergePatchPairs ( ); // ************************************************** *********************** //
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In memory of my friend Hervé: CFD engineer & freerider |
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