CFD Online Discussion Forums - snappyHexMesh: cell lower corner instead of cell centre

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andrea.pasquali

February 5, 2013 11:03

snappyHexMesh: cell lower corner instead of cell centre

Hi all,

I would like to change the criterion that snappyHexMesh uses to keep cells into the domain during the refinement stage (cast). I would like to keep in the domain all the cells that have not the cell centre but the cell lower corner into the domain.
I am trying to modify the code in the file "src/mesh/autoMesh/autoHexMesh/meshRefinement/meshRefinement.C". At line 75 there is the cell centres vector definition:

Quote:

const pointField& cellCentres = mesh_.cellCentres();

I would like to obtain the cell lower corner vector as follows:

Quote:

forAll(mesh_.points(), nodeI)
{
forAll(mesh_.cellPoints(), cellI)
{
if (mesh_.cellPoints()[cellI][0] == nodeI)
{
Info << mesh_.points()[nodeI] << endl; // this is right
const vector& cellLowerCorners = mesh_.points()[nodeI];
}
}
}

My problem is that the vector "cellLowerCorners" that I am trying to write "works" just inside the if statments. I am not able to append the values to the vector each iteration of the "for" loop.
I think I am not writing/initializing the vector correctly. Does anyone have any suggesstion?

Thanks in advance

Andrea

andrea.pasquali

February 7, 2013 08:07

Hi All,

I solved the problem using a Dynamic Vector. This is fine and I have all the cell-lower-corner in a vector.
If I am understanding correctly, OpenFOAM selects the cells that have to be deleted according to an index defined in cellRegion:

Code:

    regionSplit cellRegion(mesh_);



    DynamicList<label> cellsToRemove(mesh_.nCells());

    forAll(cellRegion, cellI)

    {

        if (cellRegion[cellI] != regionI)

        {

            cellsToRemove.append(cellI);

        }

    }

    cellsToRemove.shrink();

I guess this index is 0 when the cell-centre is in the keepPoint region and 1 when outside.
I would like to change this: no cell-centre criterion but cell-lower-corner.
Does anyone know which is the file I have to look for?

Thanks for any help

Andrea

andrea.pasquali

February 7, 2013 10:53

Now I am able to change the vector:

Code:

cellsToRemove

with a new vector where I have only the cells with the lover corner into the stl. I called it:

Code:

cellToRemoveLowerCorner

But I got problem some lines below:

Code:

    labelList exposedFaces(cellRemover.getExposedFaces(cellsToRemoveLowerCorner));



    if (exposedFaces.size())

    {

        FatalErrorIn

        (

            "meshRefinement::splitMeshRegions(const point&)"

        )   << "Removing non-reachable cells should only expose boundary faces"

            << nl

            << "ExposedFaces:" << exposedFaces << abort(FatalError);

    }

The error I got when I run snappyHexMesh is:

Quote:

--> FOAM FATAL ERROR:
Removing non-reachable cells should only expose boundary faces
ExposedFaces:8(475 477 479 481 483 485 487 488)

From function meshRefinement::splitMeshRegions(const point&)
in file autoHexMesh/meshRefinement/meshRefinement.C at line 1970.

FOAM aborting

Why now changing only the "cellsToRemove" vector I have these ExposedFaces while not before?

Thanks
Andrea

andrea.pasquali

February 11, 2013 06:21

Hi All,
finally I have it.
I changed the "edge" definition into meshRefinement.C file

andrea.pasquali

February 11, 2013 06:22

Hi All,
finally I have it. I changed the "edge" definition into the meshRefinement.C file

Andrea

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