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[snappyHexMesh] bad grid problem analysis

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Old   September 13, 2019, 04:35
Default bad grid problem analysis
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John Wang
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I am using snappyHexMesh generating grid but it always has some very strange grid at the geometry surface. Can any expert tell the reason and solution? Thanks.
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Old   September 14, 2019, 01:48
Default grid problem
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I used snappyHexMesh to generate mesh. I got this result as attached that the snap function cannnot capture the geometry (blue parts) accurately. Can any expert tell the reason and solution? Thanks.
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Old   September 15, 2019, 08:48
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The problem can be solved in some degree by adjust the snap controls setting.
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Old   September 15, 2019, 08:52
Default grid problem
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I encountered a new problem that grid at some corners of the geometry has been very weird. Can any expert tell the reason and solution?
Thanks
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Old   September 15, 2019, 08:53
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Quote:
Originally Posted by xwang252 View Post
I encountered a new problem that grid at some corners of the geometry has been very weird. Can any expert tell the reason and solution?
Thanks
Even refining the grid near the geometry would not solve this problem.
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Old   September 17, 2019, 01:32
Default grid problem
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I have finally fixed this problem.

it needs to be clarified that
SnappyHexMesh does has the capability to snap even sharp corners of the geometry. The key parameters for this problem are:
base mesh size
nCellsBetweenLevels - 6 //solve bad grids at STL surface
resolveFeatureAngle - 45 //value less than 90 could snap the perpendicular STL edge
features{*.eMesh} //solve bad/rounded grids at STL surface edge
refinementSurfaces{level(min,max)} //increase max value could help to snap edge more accurately in the same time keeping the STL surface grid size small
nSmoothPatch - 3 // setting this value a little bit larger help solve bad grid problem but not too large which would distort other good grids
nFeatureSnapIter - 5 //setting this value a little bit larger help solve bad grid problem but not too large which would increase iteration time significantly
explicitFeatureSnap - true //would help snap features
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