ENH: blob: demonstrate adding extrusion through snappyHexMesh

tutorials/mesh/cvMesh/blob/Allrun

@@ -5,7 +5,9 @@ cd ${0%/*} || exit 1    # run from this directory
 . $WM_PROJECT_DIR/bin/tools/RunFunctions
 
 runApplication blockMesh
-runApplication cvMesh $nProc
-runApplication checkMesh $nProc -constant -allGeometry -allTopology
+runApplication cvMesh
+runApplication collapseEdges 1e-3 45
+runApplication snappyHexMesh
+runApplication checkMesh -constant -allGeometry -allTopology
 
 # ----------------------------------------------------------------- end-of-file

tutorials/mesh/cvMesh/blob/system/cvMeshDict

@@ -85,7 +85,7 @@ surfaceConformation
 
     featureEdgeExclusionDistanceCoeff   0.2;
 
-    surfaceSearchDistanceCoeff  2.5;
+    surfaceSearchDistanceCoeff  5;
 
     maxSurfaceProtrusionCoeff   0.1;
 
@@ -97,7 +97,7 @@ surfaceConformation
     {
         initial
         {
-            edgeSearchDistCoeff             2;
+            edgeSearchDistCoeff             5;
             surfacePtReplaceDistCoeff       0.5;
             surfacePtExclusionDistanceCoeff 0.5;
         }
@@ -150,10 +150,16 @@ motionControl
         {
             priority            1;
             mode                bothSides;
+            surfaceCellSizeFunction uniformValue;
+            uniformValueCoeffs
+            {
+                surfaceCellSize 0.04;
+            }
+            refinementFactor    1;
+
             cellSizeFunction    uniformDistance;
             uniformDistanceCoeffs
             {
-                cellSize        0.04;
                 distance        0.1;
             }
             linearDistanceCoeffs

tutorials/mesh/cvMesh/blob/system/snappyHexMeshDict

+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  dev                                   |
+|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    object      snappyHexMeshDict;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// Which of the steps to run
+castellatedMesh false;
+snap            false;
+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
+{
+//    motorBike.obj
+//    {
+//        type triSurfaceMesh;
+//        name motorBike;
+//    }
+//
+//    refinementBox
+//    {
+//        type searchableBox;
+//        min (-1.0 -0.7 0.0);
+//        max ( 8.0  0.7 2.5);
+//    }
+};
+
+
+
+// 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 100000;
+
+    // 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 10;
+
+    // Allow a certain level of imbalance during refining
+    // (since balancing is quite expensive)
+    // Expressed as fraction of perfect balance (= overall number of cells /
+    // nProcs). 0=balance always.
+    maxLoadUnbalance 0.10;
+
+
+    // Number of buffer layers between different levels.
+    // 1 means normal 2:1 refinement restriction, larger means slower
+    // refinement.
+    nCellsBetweenLevels 3;
+
+
+
+    // 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 "someLine.eMesh";
+        //    level 2;
+        //}
+    );
+
+
+
+    // 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
+    {
+//        motorBike
+//        {
+//            // Surface-wise min and max refinement level
+//            level (5 6);
+//
+//            // Optional specification of patch type (default is wall). No
+//            // constraint types (cyclic, symmetry) etc. are allowed.
+//            patchInfo
+//            {
+//                type wall;
+//                inGroups (motorBike);
+//            }
+//        }
+    }
+
+    // Resolve sharp angles
+    resolveFeatureAngle 30;
+
+
+    // 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
+    {
+//        refinementBox
+//        {
+//            mode inside;
+//            levels ((1E15 4));
+//        }
+    }
+
+
+    // 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 (-1 0 0);
+
+
+    // 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 0;
+
+    //- Maximum number of snapping relaxation iterations. Should stop
+    //  before upon reaching a correct mesh.
+    nRelaxIter 5;
+
+    //- Highly experimental and wip: number of feature edge snapping
+    //  iterations. Leave out altogether to disable.
+    //  Do not use here since mesh resolution too low and baffles present
+    //nFeatureSnapIter 10;
+}
+
+
+
+// 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 false;
+
+    // Per final patch (so not geometry!) the layer information
+    layers
+    {
+        blob.stl_patch1
+        {
+            nSurfaceLayers 4;
+        }
+    }
+
+    // Expansion factor for layer mesh
+    expansionRatio 1.5;
+
+    //- 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 0.02;
+
+    //- 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.
+    minThickness 0.005;
+
+    //- 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 90;
+
+    //- Maximum number of snapping relaxation iterations. Should stop
+    //  before upon reaching a correct mesh.
+    nRelaxIter 3;
+
+    // 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 1000;
+
+    // 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 17x! 90 degrees corresponds to 130 in 17x.
+    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. This has to be a positive number for tracking
+    //  to work. Set to very negative number (e.g. -1E30) to
+    //  disable.
+    //     <0 = inside out tet,
+    //      0 = flat tet
+    //      1 = regular tet
+    minTetQuality -1;   //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 0.02;
+
+    //- minimum normalised cell determinant
+    //- 1 = hex, <= 0 = folded or flattened illegal cell
+    minDeterminant 0.001;
+
+    //- minFaceWeight (0 -> 0.5)
+    minFaceWeight 0.02;
+
+    //- 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;
+
+
+// ************************************************************************* //