CFD Online Discussion Forums - [Commercial meshers] fluent3DMeshToFoam conversion problem

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fluent3DMeshToFoam conversion problem

Hello together,

I'm having some trouble with converting an .msh- Mesh into the OF- format. I'm Using fluent3DMeshToFoam. The mesh consists of tetrahedras, prisms and polyhedras. If I make fluent3DMeshToFoam the conversion happens, but if I do checkMesh, I get the following output:

Code:

/*---------------------------------------------------------------------------*\

| =========                 |                                                 |

| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |

|  \\    /   O peration     | Version:  2.2.1                                 |

|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |

|    \\/     M anipulation  |                                                 |

\*---------------------------------------------------------------------------*/

Build  : 2.2.1-57f3c3617a2d

Exec   : checkMesh -constant

Date   : Sep 25 2013

Time   : 10:59:15

Host   : "karman"

PID    : 22015

Case   : /z/pro/cfdtmp03/zachjoer/test/sim

nProcs : 1

sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

fileModificationChecking : Monitoring run-time modified files using timeStampMaster

allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

Create time

Create polyMesh for time = constant

Time = constant

Mesh stats

    points:           579505

    faces:            4478543

    internal faces:   4436101

    cells:            2060402

    faces per cell:   4.3266528

    boundary patches: 10

    point zones:      0

    face zones:       1

    cell zones:       2

Overall number of cells of each type:

    hexahedra:     0

    prisms:        674616

    wedges:        0

    pyramids:      0

    tet wedges:    717

    tetrahedra:    1383038

    polyhedra:     2031

    Breakdown of polyhedra by number of faces:

        faces   number of cells

            2   306

            3   968

            4   757

Checking topology...

    Boundary definition OK.

    Illegal cells (less than 4 faces or out of range faces) found,  number of cells: 1274

  <<Writing 1274 illegal cells to set illegalCells

    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

                    B_11     1209      641  ok (non-closed singly connected)

                    B_10    13030     6617  ok (non-closed singly connected)

                    B_13     3350     2716  ok (non-closed singly connected)

                    B_12     6488     3348  ok (non-closed singly connected)

                    B_14     3356     2719  ok (non-closed singly connected)

                     B_2     2640     1431  ok (non-closed singly connected)

                     B_4      396      228  ok (non-closed singly connected)

                     B_7      158       92  ok (non-closed singly connected)

                     B_6     4960     2506  ok (non-closed singly connected)

                     B_9     6855     3470  ok (non-closed singly connected)

Checking geometry...

    Overall domain bounding box (-0.65547 -0.3 -0.3) (1.99753 0.3 0.3)

    Mesh (non-empty, non-wedge) directions (1 1 1)

    Mesh (non-empty) directions (1 1 1)

    Boundary openness (3.2271105e-16 2.0610033e-17 -7.3297854e-17) OK.

 ***Open cells found, max cell openness: 1, number of open cells 2748

  <<Writing 2748 non closed cells to set nonClosedCells

  <<Writing 27330 cells with high aspect ratio to set highAspectRatioCells

    Minimum face area = 3.127814e-09. Maximum face area = 0.0061901726.  Face area magnitudes OK.

    Min volume = 3.8690058e-13. Max volume = 0.00015677402.  Total volume = 0.95395743.  Cell volumes OK.

    Mesh non-orthogonality Max: 88.836451 average: 17.259755

   *Number of severely non-orthogonal faces: 5758.

    Non-orthogonality check OK.

  <<Writing 5758 non-orthogonal faces to set nonOrthoFaces

    Face pyramids OK.

    Max skewness = 3.6532294 OK.

    Coupled point location match (average 0) OK.

Failed 2 mesh checks.

End

I don't know what these errors mean! Can you help me?
Best regards,
CFDnewbie147

check where are those open cells
OF write those cells in the "nonClosedCells" subset.
So you can display them in Paraview for instance
>foamToVTK -cellSet nonClosedCells

Which software did you use to generate your mesh?

Hey,

i did what you told me and those cells are everywhere (not only the non closed cells, also the illegal cells(why are they illegal? they are polyhedra with 2 or 3 faces!) and the non-orthogonal faces.

I used an enterprise intern mesher (from TAU- Code) and converted the netcdf- format- mesh to a fluent mesh. And this .msh mesh i imported via fluent3DMeshToFoam to the OF mesh format.

Can u help me what i have to do? Is this a problem caused by converting the mesh two times or is the mesh really bad???

Thank you for ur help!

If you have the possibility, try to run a check mesh in fluent

Thank you for your quick reply.

But I don't have the opportunity to check the mesh in fluent, only when I'm back at university in a few weeks. Is there a "button" for checking the mesh in fluent or how do you mean I should check the mesh?

Best regards,
cfdnewbie147

you load your mesh in fluent, then in define/check mesh:
http://www.sharcnet.ca/Software/Flue...e178.htm#21267

Quote:

Originally Posted by CFDnewbie147 (Post 453495)

Code:

/*---------------------------------------------------------------------------*\

| =========                 |                                                 |

| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |

|  \\    /   O peration     | Version:  2.2.1                                 |

|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |

|    \\/     M anipulation  |                                                 |

\*---------------------------------------------------------------------------*/

Build  : 2.2.1-57f3c3617a2d

Exec   : checkMesh -constant

Date   : Sep 25 2013

Time   : 10:59:15

Host   : "karman"

PID    : 22015

Case   : /z/pro/cfdtmp03/zachjoer/test/sim

nProcs : 1

sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).

fileModificationChecking : Monitoring run-time modified files using timeStampMaster

allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

Create time

Create polyMesh for time = constant

Time = constant

Mesh stats

    points:           579505

    faces:            4478543

    internal faces:   4436101

    cells:            2060402

    faces per cell:   4.3266528

    boundary patches: 10

    point zones:      0

    face zones:       1

    cell zones:       2

Overall number of cells of each type:

    hexahedra:     0

    prisms:        674616

    wedges:        0

    pyramids:      0

    tet wedges:    717

    tetrahedra:    1383038

    polyhedra:     2031

    Breakdown of polyhedra by number of faces:

        faces   number of cells

            2   306

            3   968

            4   757

Checking topology...

    Boundary definition OK.

    Illegal cells (less than 4 faces or out of range faces) found,  number of cells: 1274

  <<Writing 1274 illegal cells to set illegalCells

    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

                    B_11     1209      641  ok (non-closed singly connected)

                    B_10    13030     6617  ok (non-closed singly connected)

                    B_13     3350     2716  ok (non-closed singly connected)

                    B_12     6488     3348  ok (non-closed singly connected)

                    B_14     3356     2719  ok (non-closed singly connected)

                     B_2     2640     1431  ok (non-closed singly connected)

                     B_4      396      228  ok (non-closed singly connected)

                     B_7      158       92  ok (non-closed singly connected)

                     B_6     4960     2506  ok (non-closed singly connected)

                     B_9     6855     3470  ok (non-closed singly connected)

Checking geometry...

    Overall domain bounding box (-0.65547 -0.3 -0.3) (1.99753 0.3 0.3)

    Mesh (non-empty, non-wedge) directions (1 1 1)

    Mesh (non-empty) directions (1 1 1)

    Boundary openness (3.2271105e-16 2.0610033e-17 -7.3297854e-17) OK.

 ***Open cells found, max cell openness: 1, number of open cells 2748

  <<Writing 2748 non closed cells to set nonClosedCells

  <<Writing 27330 cells with high aspect ratio to set highAspectRatioCells

    Minimum face area = 3.127814e-09. Maximum face area = 0.0061901726.  Face area magnitudes OK.

    Min volume = 3.8690058e-13. Max volume = 0.00015677402.  Total volume = 0.95395743.  Cell volumes OK.

    Mesh non-orthogonality Max: 88.836451 average: 17.259755

   *Number of severely non-orthogonal faces: 5758.

    Non-orthogonality check OK.

  <<Writing 5758 non-orthogonal faces to set nonOrthoFaces

    Face pyramids OK.

    Max skewness = 3.6532294 OK.

    Coupled point location match (average 0) OK.

Failed 2 mesh checks.

End

I don't know what these errors mean! Can you help me?
Best regards,
CFDnewbie147

Hi

How you saved the fluent mesh file in ascii format?

I have no idea about it

Thanks

the msh file isn't created from fluent, but from the mesher: gambit for instance

Quote:

Originally Posted by -mAx- (Post 469439)

the msh file isn't created from fluent, but from the mesher: gambit for instance

Hi

I'm using ANSYS workbench to generate mesh

However, I have no idea to make the file in ascii format

I don't have ANSYS, so I am not helpfull
Maybe you should ask on ANSYS Meshing subforum

Hello together,

I have to say I don't know how to save a ANSYS-mesh-file in an ASCII format because I didn't use ANSYS to create this mesh. I used a selfmade python script for converting into the .msh format. I hope you will find an answer.

Best regards
CFDNewbie147

Quote:

Originally Posted by itsme_kit (Post 469459)

Hi

I'm using ANSYS workbench to generate mesh

However, I have no idea to make the file in ascii format

This reply is late, but I have found an old thread which might be useful for you:

http://www.cfd-online.com/Forums/ans...ii-format.html

With regards,
Sebastian

Greetings Sebastian,

Thanks for the late reply. It reminded me that we needed a FAQ for this. I've added it here: http://openfoamwiki.net/index.php/FA...sh_in_ASCII.3F

Best regards,
Bruno

Quote:

Originally Posted by CFDnewbie147 (Post 473098)

In the top bar in Anysy meshing there must be 'options' where you can select the format in which the mesh is exported. If not then you can look for same in work bench.

If you are using the default meshing method in Ansys meshing then it is heavily probable that you will keep receiving these errors no matter how good your mesh looks in fluent. The default meshing method creates very nice mesh in some parts and fills in rest of the part with some poor quality elements (poor for openfoam, fluent will happily except it).

You could do one of following:

1. You can always visualize elements based on their quality in Ansys meshing. Decide if they are good or not and keep on trying until you get a mesh with proper quality.

2. You can chose a method that has only one type of elements (hexa or tetra). It is more easy to control the quality of mesh if you have only one type elements by simply controlling the size.

Someone please correct me if I am wrong.