[worldsheep]

Hello everyone,

I am simulating a rotor-stator system using different methods starting from the examples provided in openfoam (ex. mixerVesselAMI2D).

Every time I use an AMI interface I get the following warings:

FOAM Warning :     From virtual void Foam::faceAreaWeightAMI::calcInterArea(Foam::label, Foam::label, Foam::scalar&, Foam::vector&) const
in file AMIInterpolation/AMIInterpolation/faceAreaWeightAMI/faceAreaWeightAMI.C at line 414    
Invalid normal for source face 0 points 3((0.00193882 0.0019985 -0.00016) (0.00188455 0.00193079 -0.00016) (0.00185038 0.00199937 -0.00016)) target face
41675 points 3((-0.00230661 0.00266591 0.00065) (-0.00225043 0.00274269 0.00065) (-0.00222007 0.00264246 0.00065))

This is independent of the solver. I get the same error for:

• Stationary MRF simulations using AMI solved with simpleFoam

• Transient sumulations using AMI solved with pimpleFoam

My mesh is generated using Salome. I mesh the rotor region and the stator region separately with netgen. To make it conformal at time zero, I import the 1D-2D elements from the rotor to mesh the stator and then make a compound with the options below:

• Processing identical groups -> Unite

• Create groups from input objects -> unchecked

• Merge coincident nodes and elements -> unckeked

The mesh is then exported using: https://github.com/nicolasedh/salomeToOpenFOAM

In the boundary file:

    AMI_in
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          41676;
        startFace       4200354;
        matchTolerance  0.0001;
        transform       noOrdering;
        neighbourPatch  AMI_out;
        AMIMethod       faceAreaWeightAMI;
        restartUncoveredSourceFace 1;
    }
    AMI_out
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          41676;
        startFace       4459504;
        matchTolerance  0.0001;
        transform       noOrdering;
        neighbourPatch  AMI_in;
        AMIMethod       faceAreaWeightAMI;
        restartUncoveredSourceFace 1;
    }

In my velocity boundary conditions:

    AMI_in
    {
        type            cyclicAMI;
        value           uniform (0 0 0);
    }
    AMI_out
    {
        type            cyclicAMI;
        value           uniform (0 0 0);
    }

In my pressure boundary condition:

    AMI_in
    {
        type            cyclicAMI;
        value           uniform 0;
    }
    AMI_out
    {
        type            cyclicAMI;
        value           uniform 0;
    }

Has anyone an idea why is this warining generated?

[s1291]

Which version of OpenFOAM?

What is the output of checkMesh?

[worldsheep]

OpenFoam version:

Version:  v2006

Below a couple of examples of checkMesh reports. the AMI warning observed in both cases. The first one:

Mesh stats
    points:           190876
    faces:            1857768
    internal faces:   1696544
    cells:            888578
    faces per cell:   4
    boundary patches: 4
    point zones:      0
    face zones:       0
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    888578
    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: 2
    The mesh has multiple regions which are not connected by any face.
  <<Writing region information to "0/cellToRegion"
  <<Writing region 0 with 579648 cells to cellSet region0
  <<Writing region 1 with 308930 cells to cellSet region1

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    AMI_in              24662    12333    ok (closed singly connected)      
    bal                 83274    41629    ok (closed singly connected)      
    AMI_out             24662    12333    ok (closed singly connected)      
    wall                28626    14317    ok (closed singly connected)      

Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    CellZone            Cells        Points       Volume       BoundingBox
    vol                 579648       125064       3.68111e-08  (-0.004095 -0.004095 -0.000154999) (0.004095 0.00409499 0.000655)

Checking geometry...
    Overall domain bounding box (-0.00787451 -0.00487512 -0.00112006) (0.00741811 0.00570438 0.00288007)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-3.42035e-17 -2.71482e-16 3.71315e-16) OK.
    Max cell openness = 2.90791e-16 OK.
    Max aspect ratio = 10.9548 OK.
    Minimum face area = 2.92422e-10. Maximum face area = 1.63665e-07.  Face area magnitudes OK.
    Min volume = 2.10844e-15. Max volume = 2.00671e-11.  Total volume = 3.88783e-07.  Cell volumes OK.
    Mesh non-orthogonality Max: 79.2463 average: 16.2884
   *Number of severely non-orthogonal (> 70 degrees) faces: 13.
    Non-orthogonality check OK.
  <<Writing 13 non-orthogonal faces to set nonOrthoFaces
    Face pyramids OK.
    Max skewness = 0.909593 OK.
    Coupled point location match (average 0) OK.

And another one with better orthogonality:

Mesh stats
    points:           456958
    faces:            4541254
    internal faces:   4200354
    cells:            2185402
    faces per cell:   4
    boundary patches: 4
    point zones:      0
    face zones:       0
    cell zones:       1

Overall number of cells of each type:
    hexahedra:     0
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    2185402
    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: 2
    The mesh has multiple regions which are not connected by any face.
  <<Writing region information to "0/cellToRegion"
  <<Writing region 0 with 1803128 cells to cellSet region0
  <<Writing region 1 with 382274 cells to cellSet region1

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    AMI_in              41676    20840    ok (closed singly connected)      
    bal                 217474   108729   ok (closed singly connected)      
    AMI_out             41676    20840    ok (closed singly connected)      
    wall                40074    20039    ok (closed singly connected)      

Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    CellZone            Cells        Points       Volume       BoundingBox
    vol                 1803128      371818       3.68115e-08  (-0.004095 -0.004095 -0.00016) (0.004095 0.004095 0.00065)

Checking geometry...
    Overall domain bounding box (-0.004495 -0.004495 -0.00056) (0.004495 0.004495 0.00105)
    Mesh has 3 geometric (non-empty/wedge) directions (1 1 1)
    Mesh has 3 solution (non-empty) directions (1 1 1)
    Boundary openness (-2.25339e-17 3.01664e-17 1.30218e-16) OK.
    Max cell openness = 3.18207e-16 OK.
    Max aspect ratio = 7.49935 OK.
    Minimum face area = 1.06534e-10. Maximum face area = 2.40282e-08.  Face area magnitudes OK.
    Min volume = 5.60321e-16. Max volume = 1.04357e-12.  Total volume = 9.63311e-08.  Cell volumes OK.
    Mesh non-orthogonality Max: 67.8572 average: 15.7974
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 1.10576 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

The message: "The mesh has multiple regions which are not connected by any face" appears because the two surfaces AMI_in and AMI_out are not connected.