こんにちは（@t_kun_kamakiri）(‘◇’)ゞ
本記事ではオープンCAEを使ってバスケットボールまわりの流れを解析するまでをまとめていきます。
最終的には以下のようになります。
バスケットボール周りの流れももう少しでできそうかなという進捗。
#OpenFOAM pic.twitter.com/WdSGRX4nGI— カマキリ🐲Python頑張る昆虫 (@t_kun_kamakiri) November 5, 2021
バスケットボールはシュートの際に1秒間に2回転ほどしているそうです。
味方にパスをするときはもっと高速で回転していると思いますが、果たして回転させるとどう違うのか考察をしていく心意気です(^^)
カマキリ
自宅で解析できる記事は他にも書いています。
その他の記事
モデル作成と勉強しながら、アウトプットのため記事にまとめていきます。
今後の予定
- 【回転するバスケットボールまわりの流れ(1)】FreeCADで作るバスケットボール
- 【回転するバスケットボールまわりの流れ(2)】OpenFOAMで無回転のバスケットボールまわりのメッシュ作成
- 【回転するバスケットボールまわりの流れ(3)】OpenFOAMで無回転のバスケットボールまわりの流れ
- 【回転するバスケットボールまわりの流れ(4)】OpenFOAMで回転のバスケットボールまわりのメッシュ作成
- 【回転するバスケットボールまわりの流れ(5)】OpenFOAMで回転するバスケットボールまわりの流れ
- 【回転するバスケットボールまわりの流れ(6)】OpenFOAMで並列化計算
- 【回転するバスケットボールまわりの流れ(7)】OpenFOAMで抗力と揚力の出力
- 【回転するバスケットボールまわりの流れ(8)】PythonスクリプトによるOpenFOAMの自動計算
頑張りますよ(‘ω’)ノ
使用環境
- Windows11
- FreeCAD：0.19
- OpenFOAM-v2012 (2012)ESI版
- Paraview：5.9.0
メッシュ作成の手順
こちらにメモ書きを記載しています。
今回は「/opt/OpenFOAM/OpenFOAM-v2012/tutorials/incompressible/simpleFoam/motorbike」のチュートリアルからコピーして使おうと思います。
ファイル構成は以下のようになっています。
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 | /mnt/c/work/openfoam/20211010_basketball_flow/002_mesh_create |--motorBike | |--0.orig | | |--U | | |--include | | | |--fixedInlet | | | |--frontBackUpperPatches | | | |--initialConditions | | |--k | | |--nut | | |--omega | | |--p | |--Allclean | |--Allrun | |--constant | | |--transportProperties | | |--triSurface | | | |--README | | |--turbulenceProperties | |--mesh1 | | |--Mesh.log | | |--a.foam | | |--constant | | | |--polyMesh | | | | |--boundary | | | | |--cellLevel | | | | |--cellZones | | | | |--faceZones | | | | |--faces | | | | |--level0Edge | | | | |--neighbour | | | | |--owner | | | | |--pointLevel | | | | |--pointZones | | | | |--points | | | | |--sets | | | | | |--addedCells | | | | | |--layerFaces | | | | |--surfaceIndex | | | |--transportProperties | | | |--triSurface | | | | |--README | | | | |--basketball.stl | | | | |--basketball_mm.stl | | | | |--internalWall-sphere.stl | | | | |--internalWall-sphere_mm.stl | | | |--turbulenceProperties | | |--sHM | | | |--0.orig | | | | |--U | | | | |--include | | | | | |--fixedInlet | | | | | |--frontBackUpperPatches | | | | | |--initialConditions | | | | |--k | | | | |--nut | | | | |--omega | | | | |--p | | | |--1 | | | | |--cellLevel | | | | |--pointLevel | | | | |--polyMesh | | | | | |--boundary | | | | | |--cellLevel | | | | | |--cellZones | | | | | |--faceZones | | | | | |--faces | | | | | |--level0Edge | | | | | |--neighbour | | | | | |--owner | | | | | |--pointLevel | | | | | |--pointZones | | | | | |--points | | | | | |--surfaceIndex | | | |--2 | | | | |--cellLevel | | | | |--pointLevel | | | | |--polyMesh | | | | | |--boundary | | | | | |--cellLevel | | | | | |--cellZones | | | | | |--faceZones | | | | | |--faces | | | | | |--level0Edge | | | | | |--neighbour | | | | | |--owner | | | | | |--pointLevel | | | | | |--pointZones | | | | | |--points | | | | | |--surfaceIndex | | | |--3 | | | | |--cellLevel | | | | |--nSurfaceLayers | | | | |--pointLevel | | | | |--polyMesh | | | | | |--boundary | | | | | |--cellLevel | | | | | |--cellZones | | | | | |--faceZones | | | | | |--faces | | | | | |--level0Edge | | | | | |--neighbour | | | | | |--owner | | | | | |--pointLevel | | | | | |--pointZones | | | | | |--points | | | | | |--sets | | | | | | |--addedCells | | | | | | |--layerFaces | | | | | |--surfaceIndex | | | | |--thickness | | | | |--thicknessFraction | | |--system | | | |--blockMeshDict | | | |--controlDict | | | |--cuttingPlane | | | |--decomposeParDict.6 | | | |--ensightWrite | | | |--forceCoeffs | | | |--fvSchemes | | | |--fvSolution | | | |--meshQualityDict | | | |--snappyHexMeshDict | | | |--streamLines | | | |--surfaceFeatureExtractDict | | | |--topoSetDict | | | |--wallBoundedStreamLines | |--mesh2 | | |--0.orig | | | |--U | | | |--include | | | | |--fixedInlet | | | | |--frontBackUpperPatches | | | | |--initialConditions | | | |--k | | | |--nut | | | |--omega | | | |--p | | |--constant | | | |--transportProperties | | | |--triSurface | | | | |--README | | | |--turbulenceProperties | | |--system | | | |--blockMeshDict | | | |--controlDict | | | |--cuttingPlane | | | |--decomposeParDict.6 | | | |--ensightWrite | | | |--forceCoeffs | | | |--fvSchemes | | | |--fvSolution | | | |--meshQualityDict | | | |--snappyHexMeshDict | | | |--streamLines | | | |--surfaceFeatureExtractDict | | | |--topoSetDict | | | |--wallBoundedStreamLines | |--system | | |--blockMeshDict | | |--controlDict | | |--cuttingPlane | | |--decomposeParDict.6 | | |--ensightWrite | | |--forceCoeffs | | |--fvSchemes | | |--fvSolution | | |--meshQualityDict | | |--snappyHexMeshDict | | |--streamLines | | |--surfaceFeatureExtractDict | | |--topoSetDict | | |--wallBoundedStreamLines |
「mesh1」と「mesh2」は後々使うため、メッシュ生成のためだけに自身で作ったフォルダです。今回は「mesh1」でメッシュを作ります。
メッシュ生成のファイル
OpenFOAMでメッシュ生成するには2つのファイルを編集して実行する必要があります。
- blockMesh
- snappyHexMesh
blockMesh
「system/blockMeshDict」のファイルを以下のように編集します。
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 | /*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 8 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; object blockMeshDict; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // convertToMeters 1; vertices ( ( -0.20 -0.20 -0.20) //0 /400mm ( 0.60 -0.20 -0.20) //1 ( 0.60 0.20 -0.20) //2 ( -0.20 0.20 -0.20) //3 ( -0.20 -0.20 0.20) //4 ( 0.60 -0.20 0.20) //5 ( 0.60 0.20 0.20) //6 ( -0.20 0.20 0.20) //7 ); blocks ( hex (0 1 2 3 4 5 6 7) (160 80 80) simpleGrading (1 1 1) //1mesh_5mm ); edges ( ); boundary ( //patch x_min_1 { type patch; faces ((0 4 7 3)); } x_max_1 { type patch; faces ((1 2 6 5)); } y_min_1 { type symmetryPlane; faces ((0 1 5 4)); } y_max_1 { type symmetryPlane; faces ((3 7 6 2)); } z_min_1 { type symmetryPlane; faces ((0 3 2 1)); } z_max_1 { type symmetryPlane; faces ((4 5 6 7)); } ); // ************************************************************************* // |
blockMeshを実行することで以下のメッシュが生成されます。
簡易バスケットボールのモデルと重ねてみて大きさを確認します。
snappyHexMesh
「system/snappyHexMeshDict」のファイルを以下のように編集します。
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 | /*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v2012 | | \\ / A nd | Website: 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 { basketball { type triSurfaceMesh; file "basketball_mm.stl"; } refinementBox { type box; min (-0.1 -0.1 -0.1); max ( 0.3 0.1 0.1); } } // 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 ( ); // 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 { basketball { // Surface-wise min and max refinement level level (1 1); // Optional specification of patch type (default is wall). No // constraint types (cyclic, symmetry) etc. are allowed. // patchInfo // { // } } } // Resolve sharp angles 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 { // refinementBox // { // } } // 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 (0.5 0.0 0.0); // Inside point // 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 2.0; //- Number of mesh displacement relaxation iterations. nSolveIter 300; //- Maximum number of snapping relaxation iterations. Should stop // before upon reaching a correct mesh. nRelaxIter 5; // Feature snapping //- Number of feature edge snapping iterations. // Leave out altogether to disable. nFeatureSnapIter 10; //- Detect (geometric only) features by sampling the surface // (default=false). implicitFeatureSnap false; //- Use castellatedMeshControls::features (default = true) explicitFeatureSnap true; //- Detect points on multiple surfaces (only for explicitFeatureSnap) multiRegionFeatureSnap false; } // 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 { "basketball" { nSurfaceLayers 5; } } // 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. // See relativeSizes parameter. finalLayerThickness 0.3; // 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 150; // At non-patched sides allow mesh to slip if extrusion direction makes // angle larger than slipFeatureAngle. slipFeatureAngle 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 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 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 // Write flags writeFlags ( scalarLevels layerSets layerFields // write volScalarField for layer coverage ); // Merge tolerance. Is fraction of overall bounding box of initial mesh. // Note: the write tolerance needs to be higher than this. mergeTolerance 1e-6; // ************************************************************************* // |
バスケットボールまわりは
作成したモデル
作成したモデルは実際に流体解析で使うのでご利用ください。
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