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[snappyHexMesh] Layers in SHM and refineWallLayer |
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April 25, 2012, 05:21 |
Layers in SHM and refineWallLayer
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#1 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
Hi,
This argument has been discussed several times but I haven't got a clear idea so far. What is the difference between the addlayer step in SHM and the refineWallLayer utility ? I've never been able to add layers in complex geometries with SHM but with rWL is simple. Unluckily the meshes obtained with the utility have usually severe non-orto and skewness problems. I already tried following the advices in this threads: http://www.cfd-online.com/Forums/ope...bent-tube.html http://www.cfd-online.com/Forums/ope...al-layers.html http://www.cfd-online.com/Forums/ope...tlet-pipe.html But I couldn't get a clear general procedure... I don't think it's a problem related to my geometries, more probably to my brain Has someone some hint ? Thanks.
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Daniele Vicario blueCFD2.1 - Windows 7 |
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April 30, 2012, 04:02 |
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#2 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
I haven't completely solved my problem yet, but I found that is more simple, with SHM, to add one layer at time.
In the enclosed picture you can see 7 layers added to a simple pipe running SHM (guess...) 7 times. finalLayerThickness is 0.9 in this case. I don't know why but setting nSurfaceLayers=7 results in no layer added. I still have to try on complex geometries.
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Daniele Vicario blueCFD2.1 - Windows 7 |
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April 30, 2012, 04:52 |
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#3 |
Senior Member
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If you post your snappyHexMesh dict I could have a look and see if I can find a reason why you don't get layers at once…
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April 30, 2012, 05:32 |
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#4 |
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 17 |
The reason is because I played too much with parameters... actually I can have 7 layers in one step if I choose the right values.
Here is my SHMDict for addlayer: Code:
addLayersControls { relativeSizes true; layers { walls { nSurfaceLayers 7; } } expansionRatio 1.1; finalLayerThickness 0.9; minThickness 0.000001; nGrow 0; featureAngle 30; nRelaxIter 5; nSmoothSurfaceNormals 1; nSmoothNormals 3; nSmoothThickness 10; maxFaceThicknessRatio 0.5; maxThicknessToMedialRatio 0.3; minMedianAxisAngle 90; nBufferCellsNoExtrude 0; nLayerIter 100; } Using my older values, expansionRatio=1.8 and finalLayerThickness=1, SHM is getting more than 100000 faces with zero volume and the results is no layer added. I'll make some more tests.
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Daniele Vicario blueCFD2.1 - Windows 7 |
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