[saidc.]

Hi,

When I'm dealing with complex geometries, after snappyHexMesh process checkMesh results says Mesh OK but topology checking says there are some "multiply connected (shared edge)". Could this cause diverge?. Is it safe to run?

Does anyone know how I can get rid of the "multiply connected edges/points"? Should I make finer mesh? Maybe better surface snapping? Because there are spheres inside a closed cylinder, so I think it should be "ok (closed singly connected)". I'm open to any advice.

checkTopologySourceCode:

if (pp.empty())
         {
             Info<< setw(34) << "ok (empty)";
         }
         else if (pTyp == TopoType::MANIFOLD)
         {
             if (pp.checkPointManifold(true, &points))
             {
                 Info<< setw(34)
                     << "multiply connected (shared point)";
             }
             else
             {
                 Info<< setw(34) << "ok (closed singly connected)";
             }
             // Add points on non-manifold edges to make set complete
             pp.checkTopology(false, &points);
         }
         else
         {
             pp.checkTopology(false, &points);
             if (pTyp == TopoType::OPEN)
             {
                 Info<< setw(34)
                     << "ok (non-closed singly connected)";
             }
             else
             {
                 Info<< setw(34)
                     << "multiply connected (shared edge)";
             }
            }

checkMesh result:

Mesh stats
    points:           37098025
    faces:            87221635
    internal faces:   75475098
    cells:            26523205
    faces per cell:   6.13412795
    boundary patches: 4
    point zones:      0
    face zones:       0
    cell zones:       2

Overall number of cells of each type:
    hexahedra:     18899402
    prisms:        1068551
    wedges:        0
    pyramids:      0
    tet wedges:    47833
    tetrahedra:    0
    polyhedra:     6507419
    Breakdown of polyhedra by number of faces:
        faces   number of cells
            4   1767222
            5   1586543
            6   1044033
            7   90552
            8   111201
            9   1031071
           10   11754
           11   62767
           12   457937
           13   2811
           14   17900
           15   238408
           16   441
           17   3181
           18   81216
           19   30
           20   147
           21   204
           23   1

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
                   Patch    Faces   Points                  Surface topology
                  wall_0    37509    40103  ok (non-closed singly connected)
                 z_min_0    16125    17664  ok (non-closed singly connected)
                 z_max_0     5445     5536  ok (non-closed singly connected)
           STL_spheres_0 11687458 14793403  multiply connected (shared edge)

Checking faceZone topology for multiply connected surfaces...
    No faceZones found.
  <<Writing 8 conflicting points to set nonManifoldPoints

Checking basic cellZone addressing...
                CellZone        Cells       Points       VolumeBoundingBox
                 square     11303831     15727867 3.72084787e-05 (-0.0163277587 -0.0163367696 0) (0.0163284519 0.0163441464 0.051)
            innerCircle     15219374     21468444 7.8549991e-05 (-0.0304956394 -0.0304956173 0) (0.0304955704 0.0304956245 0.051)

Checking geometry...
    Overall domain bounding box (-0.0304956394 -0.0304956173 0) (0.0304955704 0.0304956245 0.051)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (8.44454098e-16 -1.32861261e-17 -4.11133345e-16) OK.
    Max cell openness = 4.48864509e-16 OK.
    Max aspect ratio = 7.78430253 OK.
    Minimum face area = 2.70347356e-11. Maximum face area = 8.30936157e-07.  Face area magnitudes OK.
    Min volume = 1.00947652e-15. Max volume = 5.66587799e-10.  Total volume = 0.00011575847.  Cell volumes OK.
    Mesh non-orthogonality Max: 54.9999168 average: 14.9758969
    Non-orthogonality check OK.
    Face pyramids OK.
 ***Max skewness = 4.92403691, 10 highly skew faces detected which may impair the quality of the results
  <<Writing 10 skew faces to set skewFaces
    Coupled point location match (average 0) OK.

Failed 1 mesh checks.

End

Kind regards,
Said.