[zhernadi]

Hi there,

I am a new user of OpenFOAM and I have some problems using gmshToFoam. When I convert an .msh file for using in OpenFOAM the resulting mesh is not the same. There might be some problems with boundaries linked (I have to create 'defaultFaces' boundaries, otherwise paraFoam fails).

I use 64bit Ubuntu 10.04 with OpenFoam 1.7.0, ParaView 3.8.0 and Gmsh 2.4.2. I write down my very simple example so anyone can reproduce this problem.

1. I created an empty directory:
mkdir cuboid
cd cuboid/

2. I created a text file for the geometry:
nano cuboid.geo

Point(1) = {0, 0, 0};
Point(2) = {0, 0, 3};
Point(3) = {0, 2, 0};
Point(4) = {0, 2, 3};
Point(5) = {1, 0, 0};
Point(6) = {1, 0, 3};
Point(7) = {1, 2, 0};
Point(8) = {1, 2, 3};
Line(1) = {8, 7};
Line(2) = {7, 3};
Line(3) = {3, 4};
Line(4) = {4, 8};
Line(5) = {6, 5};
Line(6) = {5, 1};
Line(7) = {1, 2};
Line(8) = {2, 6};
Line(9) = {4, 2};
Line(10) = {6, 8};
Line(11) = {7, 5};
Line(12) = {1, 3};
Line Loop(13) = {10, -4, 9, 8};
Plane Surface(14) = {13};
Line Loop(15) = {9, -7, 12, 3};
Plane Surface(16) = {15};
Line Loop(17) = {6, 12, -2, 11};
Plane Surface(18) = {17};
Line Loop(19) = {11, -5, 10, 1};
Plane Surface(20) = {19};
Line Loop(21) = {8, 5, 6, 7};
Plane Surface(22) = {21};
Line Loop(23) = {4, 1, 2, 3};
Plane Surface(24) = {23};
Surface Loop(25) = {14, 20, 18, 22, 16, 24};
Volume(26) = {25};
Physical Surface("outlet") = {14};
Physical Surface("noslipwall") = {20, 24, 16, 22};
Physical Surface("inlet") = {18};
Physical Volume(27) = {26};

3. I created the mesh in cuboid.msh with this command:
gmsh cuboid.geo -3

4. I created three files as follows.

mkdir system 0
cp $FOAM_TUTORIALS/incompressible/icoFoam/elbow/system/controlDict system/
nano 0/p

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
dimensions      [0 2 -2 0 0 0 0];
internalField   uniform 0;
boundaryField
{
    noslipwall          
    {
        type            zeroGradient;
    }
    inlet
    {
        type            zeroGradient;
    }
    outlet 
    {
        type            fixedValue;
        value           uniform 0;
    }
    defaultFaces
    {
        type            fixedValue;
        value           uniform 0;
    }
}

nano 0/U

FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
dimensions      [0 1 -1 0 0 0 0];
internalField   uniform (0 0 0);
boundaryField
{
    noslipwall          
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    inlet
    {
        type            fixedValue;
        value           uniform (0 0 1);
    }
    outlet 
    {
        type            zeroGradient;
    }
    defaultFaces 
    {
        type            zeroGradient;
    }
}

5. I converted the Gmsh mesh to OpenFoam with this command:
gmshToFoam cuboid.msh

At this point I noticed a warning message:

--> FOAM Warning :
From function polyMesh::polyMesh(... construct from shapes...)
in file meshes/polyMesh/polyMeshFromShapeMesh.C at line 576
Found 372 undefined faces in mesh; adding to default patch.

6. I copied some files for solving the model:
cp $FOAM_TUTORIALS/incompressible/icoFoam/elbow/system/fvS* system/
cp $FOAM_TUTORIALS/incompressible/icoFoam/elbow/constant/transportProperties constant/

7. I studied the mesh in ParaView using paraFoam command and I noticed that the mesh is not the same and the boundary definitions are not correct.



8. I tried to run icoFoam and it solved the model without problems, but the solution is not realistic.

I think the problem comes from gmshToFoam, the OpenFOAM mesh is not the same as Gmsh mesh. Can you help me using a Gmsh mesh in OpenFOAM? If you can share any (tutorial) model for creating an OpenFOAM model using a Gmsh mesh, it would be also highly appreciated.

Thank you,
Zoltan