surfaceFeatureExtract
続いてsltファイルを元に特徴線を作成します。
これは次のsnappyHexMeshで使用されます。
system/surfaceFeatureExtractDict
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | geom.stl { extractionMethod extractFromSurface; // Mark edges whose adjacent surface normals are at an angle less // than includedAngle as features // - 0 : selects no edges // - 180: selects all edges includedAngle 150; // Write options writeFeatureEdgeMesh yes; // Write features to obj format for postprocessing writeObj yes; } |
snappyHexMesh
続いてstlファイルを元に形状に沿ってメッシュ作成します。
snappyHexMeshの中身は長いですが全部書いておきます。
system/snappyHexMeshDict
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 | // Which of the steps to run castellatedMesh true; snap true; addLayers false; // 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 { geom.stl { type triSurfaceMesh; name geom; } } // 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; // Number of buffer layers between different levels. // 1 means normal 2:1 refinement restriction, larger means slower // refinement. nCellsBetweenLevels 2; // 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 "geom.extendedFeatureEdgeMesh"; //"geom.eMesh"; level 1; } ); // 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 { geom { // Surface-wise min and max refinement level level (1 1); } } // 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. locationsInMesh ( (( 0.005 0.005 0.005) heater) (( 0.05 0.005 0.005) rightSolid) ((-0.05 0.005 0.005) leftSolid) ((-0.05 0.015 0.005) topAir) ((-0.05 -0.015 0.005) bottomAir) ); // 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 false; } // 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 1.0; //- Number of mesh displacement relaxation iterations. nSolveIter 30; //- Maximum number of snapping relaxation iterations. Should stop // before upon reaching a correct mesh. nRelaxIter 5; //- Highly experimental and wip: number of feature edge snapping // iterations. Leave out altogether to disable. // Of limited use in this case since faceZone faces not handled. nFeatureSnapIter 10; } // Settings for the layer addition. addLayersControls { relativeSizes true; // Per final patch (so not geometry!) the layer information layers { maxY { nSurfaceLayers 3; } } // Expansion factor for layer mesh expansionRatio 1.3; // 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. // See relativeSizes parameter. finalLayerThickness 1; // 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 0.1; // 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 1.7.x! (didn't do anything in 1.7.x) nGrow 0; // Advanced settings // When not to extrude surface. 0 is flat surface, 90 is when two faces // are perpendicular featureAngle 30; // 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 2; // Stop layer growth on highly warped cells maxFaceThicknessRatio 0.5; // Reduce layer growth where ratio thickness to medial // distance is large maxThicknessToMedialRatio 1; // Angle used to pick up medial axis points // Note: changed(corrected) w.r.t 1.7.x! 90 degrees corresponds to 130 // in 1.7.x. minMedialAxisAngle 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 { #include "meshQualityDict" // Advanced //- Number of error distribution iterations nSmoothScale 4; //- Amount to scale back displacement at error points errorReduction 0.75; } // Advanced // Merge tolerance. Is fraction of overall bounding box of initial mesh. // Note: the write tolerance needs to be higher than this. mergeTolerance 1e-6; |
大事なのはcastellatedMeshControlsの{}の中の以下の部分です。
1 2 3 4 5 6 7 8 | locationsInMesh ( (( 0.005 0.005 0.005) heater) (( 0.05 0.005 0.005) rightSolid) ((-0.05 0.005 0.005) leftSolid) ((-0.05 0.015 0.005) topAir) ((-0.05 -0.015 0.005) bottomAir) ); |
これによりsnappyHexMeshを実行するとstl面で区切られた部分の領域は名前が付けられたcellZoneができます。
1 | snappyHexMesh -overwrite |
constant/polyMesh/cellZones
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | 5 (heater { type cellZone; cellLabels List<label> 640 ... (省略) ... 163 166 ) ; } leftSolid { type cellZone; cellLabels List<label> 1040 ( 150 ... (省略) ... |
こんな形でできています。
ParaViewで確認することもできます。
※以下補足です。
snappyHexMeshはstlファイルで区切られた領域のメッシュを作成するために、locationInMeshを使うことがあります。
試しに上記をコメントアウトして以下のようにしてsnappyHexMeshを実行してみます。
1 2 3 4 5 6 7 8 9 10 | // (( 0.005 0.005 0.005) heater) // (( 0.05 0.005 0.005) rightSolid) // ((-0.05 0.005 0.005) leftSolid) // ((-0.05 0.015 0.005) topAir) // ((-0.05 -0.015 0.005) bottomAir) // ); locationInMesh ( 0.005 0.005 0.005 ); |
これだとheaterの部分しか作られていないですね。
これがlocationInMeshとlocationsInMeshの違いです。
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