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Old   March 19, 2016, 08:42
Question SurfaceMesh "problemFaces"
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Hello,

I am trying to solve a case that involves a fairly complex geometry (riverbed with additional structure). I received the riverbed in .stl format and it was of a rather low quality so I used SolidWorks (SW) to clean it up and model the additional structure that was needed for the geometry model. The cleaning of the riverbed model was basically just deleting triangles that involved sharp corners and unrealistic representation of the real surface, using "Filled Boundary" in SW to introduce smoother surfaces.

I export the surfaces to separate .stl files and then use "cat" or "surfaceAdd" to concatenate the files together in a one .stl file with regions. This is the output of my surfaceCheck:

Code:
Reading surface from "total.stl" ...

Statistics:
Triangles    : 8365
Vertices     : 4497
Bounding Box : (1e-06 1e-06 100) (122.14 249.327 114)

Region    Size
------    ----
inlet    2256
walli    4944
wall-river    50
wall-fleyti    253
atmo-top    240
atmo-horiz    119
outlet-river    2
outlet-fleyti    501


Surface has no illegal triangles.

Triangle quality (equilateral=1, collapsed=0):
    0 .. 0.05  : 0.161626
    0.05 .. 0.1  : 0.0676629
    0.1 .. 0.15  : 0.048416
    0.15 .. 0.2  : 0.0420801
    0.2 .. 0.25  : 0.0369396
    0.25 .. 0.3  : 0.0425583
    0.3 .. 0.35  : 0.0361028
    0.35 .. 0.4  : 0.032636
    0.4 .. 0.45  : 0.0276151
    0.45 .. 0.5  : 0.0310819
    0.5 .. 0.55  : 0.0213987
    0.55 .. 0.6  : 0.0218769
    0.6 .. 0.65  : 0.0237896
    0.65 .. 0.7  : 0.0518828
    0.7 .. 0.75  : 0.128512
    0.75 .. 0.8  : 0.154094
    0.8 .. 0.85  : 0.0228332
    0.85 .. 0.9  : 0.01841
    0.9 .. 0.95  : 0.0160191
    0.95 .. 1  : 0.014465

    min 2.13856e-11 for triangle 5393
    max 0.999792 for triangle 2342

Edges:
    min 0.000280529 for edge 10494 points (96.3715 69.6728 105)(96.3717 69.6726 105)
    max 90.1672 for edge 11019 points (11.8551 135.061 114)(98.2565 109.275 114)

Checking for points less than 1e-6 of bounding box ((122.14 249.327 14) metre) apart.
Found 0 nearby points.

Surface is not closed since not all edges connected to two faces:
    connected to one face : 902
    connected to >2 faces : 11
Conflicting face labels:935
Dumping conflicting face labels to "problemFaces"
Paste this into the input for surfaceSubset

Number of unconnected parts : 9
Splitting surface into parts ...

Writing zoning to "zone_total.vtk"...

writing part 0 size 7562 to "total_0.obj"
writing part 1 size 31 to "total_1.obj"
writing part 2 size 72 to "total_2.obj"
writing part 3 size 53 to "total_3.obj"
writing part 4 size 25 to "total_4.obj"
writing part 5 size 93 to "total_5.obj"
writing part 6 size 15 to "total_6.obj"
writing part 7 size 13 to "total_7.obj"
writing part 8 size 501 to "total_8.obj"

Number of zones (connected area with consistent normal) : 22
More than one normal orientation.


End
The "problemFaces" where edges are connected to either one or >2 faces is where the SW surfaces are adjacent to the original riverbed surface or other SW surfaces. This is because SW exports the surfaces as separate surfaces, so the surfaceMesh of the surfaces do not conform to each other. But I am not sure how this really affects the meshing procedure since the geometry is watertight. An example of this is shown below:



How critical are the "problemFaces" from the surfaceCheck output for the meshing process when originating from the situation I show in the image above, that is when adjacent faces do not share the same edge?





Last edited by fusij; March 21, 2016 at 05:58.
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