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[snappyHexMesh] SHM Boundaryproblems with an STL-File

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Old   November 24, 2020, 00:24
Default SHM Boundaryproblems with an STL-File
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Hello, i need your help, at my first meshing attempt with an STL-File. The STL-File ist shown below, its shape is very similar to the Dambreak tutorial. The overall lenght is about 2 m.


I do a "background" Mesh with blockMesh, all edges are 3 m long, to cover the whole STL Geometry.


After that, i do the "snappyHexMesh" command. Obviously the mesh is build right.



If i open up the case with parafoam, the consols shows many warnings.


Code:
kai@Kai-Desktop:~/OpenFOAM/kai-7/run/tutorials_of/multiphase/interFoam/laminar/damBreak_stl/damBreak$ paraFoam
I/O    : uncollated
--> FOAM Warning : 
    From function virtual Foam::polyMesh::readUpdateState Foam::polyMesh::readUpdate()
    in file meshes/polyMesh/polyMeshIO.C at line 209
    unexpected consequences.  Proceed with care.
--> FOAM Warning : 
    From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList<Foam::wordRe>&, bool, bool) const
    in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 804
    Cannot find any patch or group names matching left
--> FOAM Warning : 
    From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList<Foam::wordRe>&, bool, bool) const
    in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 804
    Cannot find any patch or group names matching end
--> FOAM Warning : 
    From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList<Foam::wordRe>&, bool, bool) const
    in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 804
    Cannot find any patch or group names matching front
--> FOAM Warning : 
    From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList<Foam::wordRe>&, bool, bool) const
    in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 804
    Cannot find any patch or group names matching bottom
--> FOAM Warning : 
    From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList<Foam::wordRe>&, bool, bool) const
    in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 804
    Cannot find any patch or group names matching top
--> FOAM Warning : 
    From function Foam::labelHashSet Foam::polyBoundaryMesh::patchSet(const Foam::UList<Foam::wordRe>&, bool, bool) const
    in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 804
    Cannot find any patch or group names matching right
--> FOAM Warning : 
    From function virtual Foam::polyMesh::readUpdateState Foam::polyMesh::readUpdate()
    in file meshes/polyMesh/polyMeshIO.C at line 209
    unexpected consequences.  Proceed with care.
Before im trying to open up the case, i do a checkMesh.

Here are the results.
Code:
/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  7
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
Build  : 7-1ff648926f77
Exec   : checkMesh
Date   : Nov 24 2020
Time   : 05:59:41
Host   : "Kai-Desktop"
PID    : 6898
I/O    : uncollated
Case   : /home/kai/OpenFOAM/kai-7/run/tutorials_of/multiphase/interFoam/laminar/damBreak_stl/damBreak
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 0

Time = 0 // blockMesh

Mesh stats
    points:           29791
    faces:            83700
    internal faces:   78300
    cells:            27000
    faces per cell:   6
    boundary patches: 6
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     27000
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

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                  
    left                900      961      ok (non-closed singly connected)  
    end                 900      961      ok (non-closed singly connected)  
    front               900      961      ok (non-closed singly connected)  
    bottom              900      961      ok (non-closed singly connected)  
    top                 900      961      ok (non-closed singly connected)  
    right               900      961      ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (0 -3 0) (3 0 3)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (1.29976e-16 1.46295e-16 6.22894e-17) OK.
    Max cell openness = 2.77556e-16 OK.
    Max aspect ratio = 1 OK.
    Minimum face area = 0.01. Maximum face area = 0.01.  Face area magnitudes OK.
    Min volume = 0.001. Max volume = 0.001.  Total volume = 27.  Cell volumes OK.
    Mesh non-orthogonality Max: 0 average: 0
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 3.10887e-14 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

--> FOAM Warning : 
    From function virtual Foam::polyMesh::readUpdateState Foam::polyMesh::readUpdate()
    in file meshes/polyMesh/polyMeshIO.C at line 209
    unexpected consequences.  Proceed with care.
Time = 0.001 // snappyHexMesh

Mesh stats
    points:           68306
    faces:            194580
    internal faces:   184620
    cells:            63200
    faces per cell:   6
    boundary patches: 1
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     63200
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

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                  
    CAD                 9960     9962     ok (closed singly connected)      

Checking geometry...
    Overall domain bounding box (0 -2 0) (2 0 2)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-1.66453e-16 2.37027e-16 -3.06715e-16) OK.
    Max cell openness = 2.77556e-16 OK.
    Max aspect ratio = 1 OK.
    Minimum face area = 0.0025. Maximum face area = 0.0025.  Face area magnitudes OK.
    Min volume = 0.000125. Max volume = 0.000125.  Total volume = 7.9.  Cell volumes OK.
    Mesh non-orthogonality Max: 0 average: 0
    Non-orthogonality check OK.
    Face pyramids OK.
Due to the checkMesh results, i think i "lose" my boundarypatches, at the snappyhexmesh mesh.

I look into the tutorial, but i didnt find a way, or overread it, to transfer the boundarys to the snappyhexmesh.


How can it be done ?


Best regards
Kai
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Old   December 12, 2020, 09:27
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it was my fault. The STL File contains only one Patchname. I edited it with Blender and save all the parts with different Patchnames. Now it works perfectly
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Old   May 10, 2022, 07:50
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i got the same errors. the reason is the named patch contains no faces in STL file.
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