[mgab]

Hi,
i'm trying to create a simple mesh (i'm just learning openFoam) shaped like a T upside-down.
This is the blockMeshDict:

convertToMeters 0.1;

vertices
(
    (0 0 0)
    (20 0 0)
    (20 1 0)
    (0 1 0)
    (0 0 0.1 )
    (20 0 0.1 )
    (20 1 0.1 )
    (0 1 0.1 )
    (5 1 0)
    (6 1 0)
    (6 1 0.1)
    (5 1 0.1)
    (5 4 0)
    (6 4 0)
    (6 4 0.1)
    (5 4 0.1)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (20 20 1) simpleGrading (1 1 1)
    hex (8 9 10 11 12 13 14 15) (20 20 1) simpleGrading (1 1 1)
);


edges
(
);

boundary
(
    top
    {
        type wall ;
        faces
        (
            (3 7 11 8)
            (8 11 15 12)
            (14 10 9 13)
            (9 10 6 2)
        );
    }
    bottom
    {
        type wall ;
        faces
        (
            (1 5 4 0)
        );
    }
    inlet1
    {
        type patch ;
        faces
        (
            (0 4 7 3)
        );
    }
    inlet2
    {
        type patch ;
        faces
        (
            (12 15 14 13)
        );
    }

    outlet
    {
        type patch ;
        faces
        (
            (2 6 5 1)
        );
    }
    frontAndBack
    {
        type empty ;
        faces
        (
            (0 3 2 1)
            (4 5 6 7)
        );
    }
);

mergePatchPairs
(
);

When try to compile the mesh i get the following warning and error:

zero or negative pyramid volume: -0.05 for face 0

for faces 0 to 5.
And also

--> FOAM FATAL ERROR: 
face 0 in patch 0 does not have neighbour cell face: 4(3 7 11 8)

Does anyone know what i did wrong?
Thanks

[mgab]

I found one mistake in the order of the vertices.

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.1;

vertices
(
    (0 0 0)        //0
    (20 0 0)    //1
    (20 1 0)    //2
    (0 1 0)        //3
    (0 0 0.1 )    //4
    (20 0 0.1 )    //5
    (20 1 0.1 )    //6
    (0 1 0.1 )    //7
    (5 1 0)        //8
    (6 1 0)        //9
    (6 4 0)        //10
    (5 4 0)        //11
    (5 1 0.1)    //12
    (6 1 0.1)    //13
    (6 4 0.1)    //14
    (5 4 0.1)    //15
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (20 20 1) simpleGrading (1 1 1)
    hex (8 9 10 11 12 13 14 15) (20 20 1) simpleGrading (1 1 1)
);


edges
(
);

boundary
(
    top
    {
        type wall ;
        faces
        (
            (8 3 7 12)
            (8 12 15 11)
            (14 13 9 10)
            (9 13 6 2)
        );
    }
    bottom
    {
        type wall ;
        faces
        (
            (1 5 4 0)
        );
    }
    inlet1
    {
        type patch ;
        faces
        (
            (0 4 7 3)
        );
    }
    inlet2
    {
        type patch ;
        faces
        (
            (11 15 14 10)
        );
    }

    outlet
    {
        type patch ;
        faces
        (
            (2 6 5 1)
        );
    }
    frontAndBack
    {
        type empty ;
        faces
        (
            (0 3 2 1)
            (4 5 6 7)
        );
    }
);

mergePatchPairs
(
);
// ************************************************************************* //

but the fatal error remains

Create time

Creating block mesh from
    "/home/marco/OpenFOAM/marco-4.1/run/prova/constant/polyMesh/blockMeshDict"
Creating curved edges
Creating topology blocks
Creating topology patches

Creating block mesh topology


--> FOAM FATAL ERROR: 
face 0 in patch 0 does not have neighbour cell face: 4(8 3 7 12)

    From function Foam::labelList Foam::polyMesh::facePatchFaceCells(const faceList&, const labelListList&, const faceListList&, Foam::label) const
    in file meshes/polyMesh/polyMeshFromShapeMesh.C at line 118.

FOAM aborting

#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::error::abort() at ??:?
#2  Foam::polyMesh::facePatchFaceCells(Foam::List<Foam::face> const&, Foam::List<Foam::List<int> > const&, Foam::List<Foam::List<Foam::face> > const&, int) const at ??:?
#3  Foam::polyMesh::setTopology(Foam::List<Foam::cellShape> const&, Foam::List<Foam::List<Foam::face> > const&, Foam::List<Foam::word> const&, Foam::List<int>&, Foam::List<int>&, int&, int&, Foam::List<Foam::cell>&) at ??:?
#4  Foam::polyMesh::polyMesh(Foam::IOobject const&, Foam::Xfer<Foam::Field<Foam::Vector<double> > > const&, Foam::List<Foam::cellShape> const&, Foam::List<Foam::List<Foam::face> > const&, Foam::List<Foam::word> const&, Foam::PtrList<Foam::dictionary> const&, Foam::word const&, Foam::word const&, bool) at ??:?
#5  Foam::blockMesh::createTopology(Foam::IOdictionary const&, Foam::word const&) at ??:?
#6  Foam::blockMesh::blockMesh(Foam::IOdictionary const&, Foam::word const&) at ??:?
#7  ? at ??:?
#8  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#9  ? at ??:?
Aborted

[Antimony]

Hi,

In neither of your blocks do you have any surface that contains all the vertices 8, 3, 7 and 12.

In order for you to define a boundary, the vertices should together be part of a block, which is not the case.

Hope this helps.

Cheers,
Antimony

[mgab]

Hi,
i thought that blocks wouldn't need same vertices.
Thanks

[Bob!]

Hey

Your Problem isn't the block or it's points, that seems to be right;
your Problem is, that you are defining a face (of the wall "Top") over two blocks. that is just not possible. check your points and the faces you want to build, maybe write them down and draw your geometry and you will see, what you'll have to change.

best regards