[geth03]

hi all,

i was playing around with shm for a very basic case, just a cube inside a background mesh (see attachment).

my mesh is rather coarse, i was testing the limits of boundary layer extrusion compared with the rather coarse background mesh.

during the boundary layer addition steps the mesh control does not complain about quality:

Checking mesh with layer ...
Checking faces in error :
    non-orthogonality > 70  degrees                        : 0
    faces with skewness > 4   (internal) or 20  (boundary) : 0
Detected 0 illegal faces (concave, zero area or negative cell pyramid volume)
Extruding 24 out of 24 faces (100%). Removed extrusion at 0 faces.
Added 792 out of 792 cells (100%).
Edge intersection testing:
    Number of edges             : 35760
    Number of edges to retest   : 0
    Number of intersected edges : 816
Writing 792 added cells to cellSet addedCells
Writing 768 faces inside added layer to faceSet layerFaces

Writing fields with layer information:
    nSurfaceLayers    : actual number of layers
    thickness         : overall layer thickness
    thicknessFraction : overall layer thickness (fraction of desired thickness)


patch faces    layers   overall thickness
                      [m]       [%]
----- -----    ------   ---       ---
Box 24       33       6.12      50

Layer mesh : cells:11432  faces:35760  points:13024
Cells per refinement level:
    0   11432
Writing mesh to time constant
Wrote mesh in = 0.121854 s.
Layers added in = 0.12185 s.
Checking final mesh ...
Checking faces in error :
    non-orthogonality > 70  degrees                        : 0
    faces with skewness > 4   (internal) or 20  (boundary) : 0
Finished meshing without any errors
Finished meshing in = 1.01829 s.
End

however, when i execute checkmesh in stand-alone mode, i get this:

Checking geometry...
    Overall domain bounding box (-40 -40 -40) (50 50 50)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
 ***High aspect ratio cells found, Max aspect ratio: 1967.29, number of cells 48
    Minimum face area = 0.0126368. Maximum face area = 81.8758.  Face area magnitudes OK.
    Min volume = 0.0552352. Max volume = 349.537.  Total volume = 728000.  Cell volumes OK.
    Mesh non-orthogonality Max: 81.2485 average: 7.0263
   *Number of severely non-orthogonal (> 70 degrees) faces: 27.
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 2.50041 OK.
    Coupled point location match (average 0) OK.

Failed 1 mesh checks.

End

that is a very strange behaviour.

when i increase the layer count further, i get the same outcome, but a worse quality value in checkmesh, nearly 90 max value for non-ortho..

[geth03]

oh crap, i found it.
i was saving in ascii with limited precision,
when i changed to binary the discrepancy disappeared.
my bad.