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no snapping to features

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Old   October 26, 2015, 10:12
Default no snapping to features
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Duncan Roy van der Heul
Join Date: May 2010
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Dear All,

I am trying to mesh an old case that did not present a problem with an older version of snappyHexMesh.

The problem is that for a coarse discretisation the mesh (nearly) correctly snaps to the
features in the grid, but not when the mesh is refined.

The first picture shows the mesh, with strong refinement near a kink in the surface that snappyHexMesh does not want to resolve. The second picture shows (in red) the features extracted.

Does anybody know the reason for this behavior?
Here is an exempt from the snappyHexMeshDict. I tried changing the number of
iterations, but observed no effect.

Code:
snapControls
{
    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 15;

    //- Maximum number of snapping relaxation iterations. Should stop
    //  before upon reaching a correct mesh.
    nRelaxIter 15;

    // Feature snapping

        //- Number of feature edge snapping iterations.
        //  Leave out altogether to disable.
        nFeatureSnapIter 45;

        //- Detect (geometric only) features by sampling the surface
        //  (default=false).
        implicitFeatureSnap true;

        //- Use castellatedMeshControls::features (default = true)
        explicitFeatureSnap true;

        //- Detect points on multiple surfaces (only for explicitFeatureSnap)
        multiRegionFeatureSnap true;
}
Attached Images
File Type: jpg no_snap.jpg (205.8 KB, 15 views)
File Type: jpg no_snap_edges.jpg (206.1 KB, 15 views)
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