# [blockMesh] Problem with mesh. non closed cells.

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April 2, 2013, 14:06
Problem with mesh. non closed cells.
#1
Senior Member

Alexander
Join Date: Apr 2013
Posts: 1,600
Rep Power: 23
Here i attach some pictures to describe the problem.

Domain is a cylinder that consists of 5 hexa-blocks. Non closed cells appears on front and back surfaces of central block.

Here is blockMeshDict:

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.0.1 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 2.53e-02;

vertices
(
(0 0.31496063 0) //0
(1.423423083 0.31496063 0) //1
(1.423423083 0.393700787 0) //2
(0 0.393700787 0) //3
(0 0.787401575 -0.472440945) //4
(1.423423083 0.787401575 -0.472440945) //5
(1.423423083 0.787401575 -0.393700787) //6
(0 0.787401575 -0.393700787) //7
(1.423423083 1.25984252 0) //8
(0 1.25984252 0) //9
(0 1.181102362 0) //10
(1.423423083 1.181102362 0) //11
(0 0.787401575 0.3937007) //12
(1.423423083 0.787401575 0.393700787) //13
(0 0.787401575 0.472440945) //14
(1.423423083 0.787401575 0.472440945) //15

);

blocks
(
hex (0 1 2 3 4 5 6 7)
(25 25 25)

hex (4 5 6 7 9 8 11 10)
(25 25 25)

hex (9 8 11 10 14 15 13 12)
(25 25 25)

hex (14 15 13 12 0 1 2 3)
(25 25 25)

hex (3 2 6 7 12 13 11 10)
(25 25 25)

);

edges
(
arc 0 4 (0 0.551181102 -0.40914586)
arc 1 5 (1.423423083 0.551181102 -0.40914586)
arc 4 9 (0 1.023622047 -0.40914586)
arc 5 8 (1.423423083 1.023622047 -0.40914586)
arc 9 14 (0 1.023622047 0.40914586)
arc 8 15 (1.423423083 1.023622047 0.40914586)
arc 14 0 (0 0.551181102 0.40914586952)
arc 15 1 (1.423423083 0.551181102 0.40914586952)

);

boundary
(

inlet
{
type patch;
faces
(
(0 4 7 3)
(4 9 10 7)
(9 14 12 10)
(14 0 3 12)
(3 7 10 12)

);
}

wall
{
type wall;
faces
(
(0 1 5 4)
(4 5 8 9 )
(9 8 15 14)
(14 15 1 0)

);
}

outlet
{
type patch;
faces
(
(1 5 6 2)
(5 8 11 6)
(8 15 13 11)
(15 1 2 13)
(2 6 11 13)

);
}

);

mergePatchPairs
(
);

// ************************************************** *********************** //

And checkMesh feedback:

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.0.1 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 2.0.1-51f1de99a4bc
Exec : checkMesh
Date : Apr 03 2013
Time : 00:42:07
Host : ************
PID : 3167
Case : ************
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: 82576
faces: 238750
internal faces: 230000
cells: 78125
boundary patches: 3
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 78125
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 0

Checking topology...
Boundary definition 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
inlet 3125 3176 ok (non-closed singly connected)
wall 2500 2600 ok (non-closed singly connected)
outlet 3125 3176 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (0 0.0079685 -0.0119528) (0.0360126 0.031874 0.0119528)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (1.2176e-08 -6.48171e-16 -1.31418e-16) OK.
***Open cells found, max cell openness: 1, number of open cells 2400
<<Writing 2400 non closed cells to set nonClosedCells
<<Writing 62500 cells with high aspect ratio to set highAspectRatioCells
Minumum face area = 3.81022e-08. Maximum face area = 1.08166e-06. Face area magnitudes OK.
Min volume = 2e-300. Max volume = 4.57339e-10. Total volume = 6.95536e-06. Cell volumes OK.
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#2 in "/lib/libc.so.6"
#3 in "/lib/libm.so.6"
#4 acos in "/lib/libm.so.6"
#5 Foam:rimitiveMesh::checkFaceOrthogonality(bool, Foam::HashSet<int, Foam::Hash<int> >*) const in "/opt/openfoam201/platforms/linux64GccDPOpt/lib/libOpenFOAM.so"
#6
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/checkMesh"
#7
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/checkMesh"
#8 __libc_start_main in "/lib/libc.so.6"
#9
in "/opt/openfoam201/platforms/linux64GccDPOpt/bin/checkMesh"
Floating point exception

Attached Images
 Screenshot-1.jpg (30.1 KB, 27 views) Screenshot-2.jpg (30.6 KB, 27 views) Screenshot-3.jpg (70.8 KB, 38 views) Screenshot-4.jpg (62.8 KB, 31 views) Screenshot-5.jpg (58.3 KB, 24 views)

 April 3, 2013, 09:44 #2 Senior Member   Alexander Join Date: Apr 2013 Posts: 1,600 Rep Power: 23 Already solved this problem. It turned out that the important role played by the ordering of the vertices of the blocks. The first block is specified coordinate system grid: 0 1 is the X-axis, 1 2 is the Y-axis, and this axis is 0 4 is the Z-axis. All other units must be located in these coordinates as much as possible. Sorry for my bad english .

 Tags non closed cells