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difference between patches and mergePatchPairs

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Old   September 16, 2013, 09:08
Default difference between patches and mergePatchPairs
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belkadi
Join Date: May 2013
Location: France
Posts: 31
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Dear FOAMers,

I've a question :
1. In the blockMeshDict file what is the difference between the patches and mergePatchPairs key words. In fact I've prepared a mesh and I found out that using the patches leads to an error message :
face o in patch 3 does not have neigbour cell face : 4(13 12 15 14)
If I replance the mergePatchPairs by patches the error message disapear.
To be honest I don't know what should I use patches or mergePatchPairs ?

2. When using the patches, I've checked my mesh by the the checkMesh and I got the follwing error message :

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 2.2.1-57f3c3617a2d
Exec : checkMesh
Date : Sep 16 2013
Time : 14:59:50
Host : "belkadi-Latitude-E4300"
PID : 19644
Case : /home/belkadi/OpenFOAM/belkadi-2.2.1/run/tutorials/MyFirstCase/exercise/maillage_sérieux/simple_cylinder_injector_v3
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
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: 12272
faces: 34200
internal faces: 31800
cells: 11000
faces per cell: 6
boundary patches: 1
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 11000
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: 2
The mesh has multiple regions which are not connected by any face.
<<Writing region information to "0/cellToRegion"

Checking patch topology for multiply connected surfaces...
Patch Faces Points Surface topology
defaultFaces 2400 2404 ok (closed singly connected)

Checking geometry...
Overall domain bounding box (-1.76777 -2.4 -1.76777) (1.76777 4 1.76777)
Mesh (non-empty, non-wedge) directions (0 0 0)
Mesh (non-empty) directions (0 0 0)
***Number of edges not aligned with or perpendicular to non-empty directions: 10160
<<Writing 9060 points on non-aligned edges to set nonAlignedEdges
Boundary openness (5.27869e-18 -4.83497e-16 4.47807e-17) OK.
Max cell openness = 1.85401e-16 OK.
Max aspect ratio = -1 OK.
Minimum face area = 0.000484. Maximum face area = 0.282843. Face area magnitudes OK.
Min volume = 2e-300. Max volume = 0.05. Total volume = 65.7858. Cell volumes OK.
Mesh non-orthogonality Max: 180 average: 39.555
***Number of non-orthogonality errors: 2700.
<<Writing 2700 non-orthogonal faces to set nonOrthoFaces
***Error in face pyramids: 6000 faces are incorrectly oriented.
<<Writing 3300 faces with incorrect orientation to set wrongOrientedFaces
Max skewness = 2.4964 OK.
Coupled point location match (average 0) OK.

Failed 3 mesh checks.

End

Could any one help me to understand these issues ?
In attached file the source code.

Thanks in advance

Kind regards

Krimo
Attached Files
File Type: gz simple_cylinder_injector_v3.tar.gz (10.0 KB, 1 views)
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