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Mesh Generation problem

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Old   July 2, 2015, 10:20
Unhappy Mesh Generation problem
  #1
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chaitanya bhatraju
Join Date: Jun 2015
Posts: 7
Rep Power: 3
chaiitu2896 is on a distinguished road
Hi everyone
I am very new to openFoam. i tried to generate a rectangular capillary using blockMesh. and i created the structure but when i run checkMesh it is showing errors and i couldn't get them.
Below is the code for the mesh
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 100.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.001;

vertices
(
(0 0 0)
(0 0.31 0)
(0 1.39 0)
(0 1.7 0)
(25 1.7 0)
(25 1.39 0)
(25 0.31 0)
(25 0 0)
(50 0.31 0)
(50 1.39 0)
(0 0 75.5)
(0 0.31 75.5)
(0 1.39 75.5)
(0 1.7 75.5)
(25 1.7 75.5)
(25 1.39 75.5)
(25 0.31 75.5)
(25 0 75.5)
(50 0.31 75.5)
(50 1.39 75.5)
);

blocks
(
hex (0 1 6 7 10 11 16 17) (10 5 30) simpleGrading (1 1 1)
hex (1 2 5 6 11 12 15 16) (10 5 30) simpleGrading (1 1 1)
hex (2 3 4 5 12 13 14 15) (10 5 30) simpleGrading (1 1 1)
hex (5 6 8 9 15 16 18 19) (10 5 30) simpleGrading (1 1 1)
);

edges
(
);

boundary // keyword
(

plateSurface
{
type wall;
faces
(
(0 10 17 7)
(3 13 14 4)
(4 5 15 14)
(6 16 17 7)
(18 8 6 16)
(15 5 9 19)
);
}
inlet{
type patch;
faces
(
(0 1 11 10)
(2 1 11 12)
(3 2 12 13)
);
}
outlet{
type patch;
faces
(
(8 9 19 18)
);
}
);
mergePatchPairs
(
);
// ************************************************** *********************** //
Here is the error shown by checkMesh:
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.x |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
/* Windows port by CFD support (www.cfdsupport.com) [based on Symscape] *\
\*---------------------------------------------------------------------------*/
Build : 2.3.x-819030ed51bd
Exec : C:\OpenFOAM\cygwin64\opt\OpenFOAM\OpenFOAM-2.3.x\platforms\cygwin64mingw-w64DPOpt\bin\checkMesh.exe
Date : Jul 02 2015
Time : 15:14:09
Host : "CHAITANYA"
PID : 3340
Case : C:/OpenFOAM/cygwin64/home/bobby/OpenFOAM/bobby-2.3.x/run/tutorials/cavity
nProcs : 1
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
points: 7471
faces: 19400
internal faces: 16600
cells: 6000
faces per cell: 6
boundary patches: 4
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 6000
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0

Checking topology...
Boundary definition OK.
***Total number of faces on empty patches is not divisible by the number of cells in the mesh. Hence this mesh is not 1D or 2D.
Cell to face addressing OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
plateSurface 1200 1302 ok (non-closed singly connected)
inlet 900 961 ok (non-closed singly connected)
outlet 300 341 ok (non-closed singly connected)
defaultFaces 400 482 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (0 0 0) (0.05 0.0017 0.0755)
Mesh (non-empty, non-wedge) directions (1 1 0)
Mesh (non-empty) directions (1 1 0)
All edges aligned with or perpendicular to non-empty directions.
***Boundary openness (0.0205243 -3.92298e-017 -3.59784e-019) possible hole in boundary description.
***Open cells found, max cell openness: 1, number of open cells 300
<<Writing 300 non closed cells to set nonClosedCells
Minimum face area = 7.80167e-008. Maximum face area = 1.25833e-005. Face area magnitudes OK.
***Zero or negative cell volume detected. Minimum negative volume: -1.359e-009, Number of negative volume cells: 4500
<<Writing 4500 zero volume cells to set zeroVolumeCells
Mesh non-orthogonality Max: 180 average: 121.203
***Number of non-orthogonality errors: 12600.
<<Writing 12600 non-orthogonal faces to set nonOrthoFaces
***Error in face pyramids: 27300 faces are incorrectly oriented.
<<Writing 14700 faces with incorrect orientation to set wrongOrientedFaces
Max skewness = 0.375 OK.
Coupled point location match (average 0) OK.

Failed 5 mesh checks.

End

I specified boundaries as Inlet,outlet and walls(plateSurface).
I attached an image of the meshi created and also the faces that are common int the two capillary should merge. can anyone help me with the situation i'm in
Attached Images
File Type: jpg capillary_mesh.jpg (51.4 KB, 9 views)
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Old   July 10, 2015, 18:21
Default
  #2
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Alexander Bartel
Join Date: Feb 2015
Location: Germany
Posts: 97
Rep Power: 3
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Hi chaitanya,

sorry that I have overlook your thread, although your problem is pretty clear.

You have to define your blocks in the correct way.
see http://cfd.direct/openfoam/user-guid...#x25-1420005.3

"Each block has a local coordinate system that must be right-handed. "
If not the volume of the block would be negative. (first problem solved)

next problem would be, that your grading from on block to the other wouldn't fit, because the grading for each block is oriented regarding to this local coordinate system.

I hope it helps
regards
Alex
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