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-   -   [mesh manipulation] topoSet boxToFace misses faces on some sides. (https://www.cfd-online.com/Forums/openfoam-meshing/232185-toposet-boxtoface-misses-faces-some-sides.html)

akataniel December 3, 2020 10:17
topoSet boxToFace misses faces on some sides.
 
Hi all,


I have a problem with topoSet missing out Faces that should be picked by boxToFace. I have a more complex gmsh-File where I want to use topoSet but reproduced my problem with a more simple case with a 3x3x3 cube with cubic elements. The size of the complete cube is 10.0x10.0x10.0 and I am trying to pick up all faces on every side of the cube later transforming it into patches to apply BCs.


At first I convert the gmsh via gmshToFoam and then apply topoSet with the following file:



Code:
/*--------------------------------*- C++ -*----------------------------------*\
  =========                |
  \\      /  F ield        | OpenFOAM: The Open Source CFD Toolbox
  \\    /  O peration    | Website:  https://openfoam.org
    \\  /    A nd          | Version:  7
    \\/    M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version    2.0;
    format      ascii;
    class      dictionary;
    object      topoSetDict;
}

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

actions
(
    {
        name    inletFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (0.0 0.0 0.0)(10.0 0.0 10.0);
        }
    }
    {
        name    outletFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (0.0 10.0 0.0)(10.0 10.0 10.0);
        }
    }
    {
        name    bottomFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (0.0 0.0 0.0)(10.0 10.0 0.0);
        }
    }
    {
        name    topFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (0.0 0.0 10.0)(10.0 10.0 10.0);
        }
    }
        {
        name    leftFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (0.0 0.0 0.0)(0.0 10.0 10.0);
        }
    }
    {
        name    rightFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (10.0 0.0 0.0)(10.0 10.0 10.0);
        }
    }
);

// ************************************************************************* //
On the front(inlet), left and bottom side boxToFace finds all 9 Faces. But on the back(outlet), right and top side only 5 Faces are found. With modifying the box for the 3 latter ones to a 3D-Box (i.e. 10.01 - 9.99) allows to solve this problem for this easy case but not for a more complex geometry I actually want to use. I would be grateful for every hint, that allows to solve my problem.


Thank you!

Ship Designer December 18, 2020 00:30
Depending on the geometry complexity, you could try to use the utility autoPatch and play around with the angle option. It will automatically create patches named auto0, auto1 … autoN. You can then rename these and assign types with createPatch and createPatchDict. This has the limitation that if the geometry changes, the numbering of automatically created patches might change as well, requiring createPatchDict to be edited. But it still might save time. I believe you can also define patches by defining boxes or other matching criteria in the createPatchDict directly (if that's what you are trying to do) and you wouldn't need to use topoSet first.

Cheers, Claudio

Marpole December 19, 2020 12:46
It seems to me that you are not using a box but a plane. Have you tested using something slightly different, such as below.

Code:
    {
        name    outletFaces;
        type    faceSet;
        action  new;
        source  boxToFace;
        sourceInfo
        {
            box (0.0 9.999 0.0)(10.0 10.001 10.0);
        }
    }


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