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February 21, 2020, 21:57 |
problem with adding layers
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#1 |
New Member
Join Date: May 2013
Posts: 29
Rep Power: 12 |
Hello all,
I have some problems with adding layer near surface given by stl files. I have tried to add 5 layers (i.e. nSurfaceLayers 5) for all patches. Other addLayersControls settings are as follows. Code:
relativeSizes true; expansionRatio 1.2; finalLayerThickness 0.8; minThickness 0.01; nGrow 1; featureAngle 60; nRelaxIter 5; nSmoothSurfaceNormals 1; nSmoothNormals 3; nSmoothThickness 10; maxFaceThicknessRatio 0.5; maxThicknessToMedialRatio 0.3; minMedianAxisAngle 90; nBufferCellsNoExtrude 0; nLayerIter 50; nRelaxedIter 20; patch faces layers overall thickness [m] [%] ----- ----- ------ --- --- building1 617 0 0 0 building2 1419 0 0 0 ... Does anybody have some ideas about it? Leo |
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February 23, 2020, 13:17 |
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#2 |
Member
Join Date: Sep 2018
Location: France
Posts: 62
Rep Power: 7 |
Hi Leo,
Well by seeing your configuration, I think from what I have seen that Code:
nGrow 1; Also, for Code:
featureAngle 60; If these two parameters are not enough to solve the addlayer phases: For the sharp edges what you can do is increase up to 10 Code:
nSmoothSurfaceNormals For snapping setup you can increase : Code:
nSolveIter 30; For instance on a 6 millions cells, it is not affecting a lot the time for meshing but it improves a bit the snapping phase. Cheers, |
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February 24, 2020, 21:22 |
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#3 | |
New Member
Join Date: May 2013
Posts: 29
Rep Power: 12 |
Quote:
Hi John, Thank you for your help. I set nGrow = 0, featureAngle = 120 (or 150 or 180) with others unchanged (Figure angle120, angle150 and angle180). I also tried to increase nSmoothSurfaceNormals to 10 and nSolveIter to 300. Layers were successfully added but the results are far from ideal. Do you have other suggestions? Thank you, Leo |
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February 25, 2020, 04:09 |
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#4 |
Member
Join Date: Sep 2018
Location: France
Posts: 62
Rep Power: 7 |
Hi Leo,
It seems you have a bad snap. I did not see it but you forgot in your SHM dict to mention the feature snapping tools : try to add these lines in the snappingControls section just after the function nRelaxIter 5; Code:
// 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 features between multiple surfaces // (only for explicitFeatureSnap, default = false) multiRegionFeatureSnap false; |
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February 25, 2020, 09:16 |
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#5 |
Senior Member
Sita Drost
Join Date: Mar 2009
Location: Arnhem, The Netherlands
Posts: 227
Rep Power: 18 |
Hi Leo,
I'm running into similar issues when trying to mesh a ship hull. As long as I stick to the settings used in the DTCHull tutorial (3 wall layers), everything's fine, but as soon as I try to add more layers, I end up with an invalid mesh. I came across some posts by seaspray (Eric Bretscher) in this thread (posts #6 and #8). They're from 2014, so not very recent, but his strategy might be worthwhile trying. Cheers, Sita |
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February 27, 2020, 00:10 |
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#6 | |
New Member
Join Date: May 2013
Posts: 29
Rep Power: 12 |
Quote:
Hi John, You are right. The snap is bad. I have checked .stl and .eMesh and everything seems fine (Fig. building_stl and edgeMesh). But SHM can't capture edges of rooftop correctly while grid at the bottom is OK (Fig. building_snap and building_mesh2). Here are settings for snap Code:
snapControls { nSmoothPatch 3; tolerance 4.0; nSolveIter 100; nRelaxIter 5; nFeatureSnapIter 10; implicitFeatureSnap false; explicitFeatureSnap true; multiRegionFeatureSnap false; } Thank you, Leo |
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February 27, 2020, 22:24 |
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#7 |
New Member
Join Date: May 2013
Posts: 29
Rep Power: 12 |
Hi John and Sita,
Thank you for your replies. I solved this by decreasing resolveFeatureAngle. Cheers, Leo |
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