[CFDeProjekt]

Hi all,

i try to create a channel with Gmsh with a finer mesh resolution on the upper and lower wall. Then i obviously try to get this mesh work with OpenFoam via gmshToFoam.
The mesh itself in Gmsh looks good, just as i want it to be. Unfortunately i get a bunch of these error messages after hitting gmshToFoam.

examples:

-FOAM Warning :
From function polyMesh:olyMesh(... construct from shapes...)
in file meshes/polyMesh/polyMeshFromShapeMesh.C at line 627
Found 29002 undefined faces in mesh; adding to default patch.
Finding faces of patch 0

-FOAM Warning : Not using gmsh face 3(16630 11393 12381) since zero vertex is not on boundary of polyMesh

-FOAM Warning :
From function gmshToFoam
in file gmshToFoam.C at line 972
Could not match gmsh face 3(16630 11393 12381) to any of the interior or exterior faces that share the same 0th point

This is my code for the .geo file:

a = 0.01;
b = 0.1;

Point(1) = {0, 0, 0, a};
Point(2) = {10, 0, 0, a};
Point(3) = {10, 0, 0.5, b};
Point(4) = {0, 0, 0.5, b};

Line(1) = {1, 4};
Line(2) = {1, 2};
Line(3) = {2, 3};
Line(4) = {3, 4};

Point(5) = {0, 0, 1, a};
Point(6) = {10, 0, 1, a};

Line(5) = {3, 6};
Line(6) = {5, 6};
Line(7) = {4, 5};

Line Loop(8) = {2, 3, 4, -1};
Line Loop(9) = {5, -6, -7, -4};

Plane Surface(10) = {8};
Plane Surface(11) = {9};

Extrude {0, 0.1, 0}
{
Surface{10,11};
Layers{1};
Recombine;
}

Physical Volume(1) = {1};


Physical Surface("auslass") = {13, 17};
Physical Surface("einlass") = {15, 19};
Physical Surface("obenundunten") = {12, 18};
Physical Surface("vornundhinten") = {10, 11, 16, 20};

I guess the problem might be the middle plane which i constructed to get the finer resolution on the edges, because i don't know how to handle it otherwise.

with middle plane i mean this line, which is extruded to become a plane:

Line(4) = {3, 4};


Does anyone have an idea what i am doing wrong? Is it due to this middle plane? Does it have to be an physical entity?

Looking forward for any kind of help!
Thanks and Regards

[louisgag]

Hi Ewald,

Without trying the conversion myself I cannot tell whether the midplane is the issue, but if you get no error when the midplane is absent that would be a big hint for you ;-)

I looked at your mesh and you would be much better off using the

Field[expression]

options of Gmsh instead of a midplane to refine it. I use fields successfully for meshes that I then convert to OpenFOAM and experience no issues, apart from the default patch warning, with is usually nothing to worry about.

See the Gmsh manual here: http://gmsh.info/doc/texinfo/gmsh.ht...-element-sizes for more info and specifically look at the Attractor, Threshold, Min, etc. field types.

Hope this helps,


-Louis