CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Native Meshers: blockMesh

blockMesh "Number of edges not aligned with or perpendicular to non-empty direction"

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   April 24, 2014, 10:56
Default blockMesh "Number of edges not aligned with or perpendicular to non-empty direction"
  #1
New Member
 
Duarte Magalh„es
Join Date: Apr 2014
Location: Lisbon, Portugal
Posts: 24
Rep Power: 4
DuarteMagalhaes is on a distinguished road
Hi, can anyone help me on this?

When i run checkMesh i get the following error message:

"
(...)
Wedge axi_symm-r with angle 2.5 degrees
***Number of edges not aligned with or perpendicular to non-empty directions: 9360
<<Writing 5746 points on non-aligned edges to set nonAlignedEdges
(...)
Failed 1 mesh checks.
"
My blockMeshDict file is:

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

convertToMeters 1;

vertices
(
(0 0 0) //0
(0.0000436193873653360 0.000999048221581858 0) //1
(-0.0000436193873653360 0.000999048221581858 0) //2
(0.00218096936826680 0.0499524110790929 0) //3
(-0.00218096936826680 0.0499524110790929 0) //4
(0 0 0.2) //5
(0.0000436193873653360 0.000999048221581858 0.2) //6
(-0.0000436193873653360 0.000999048221581858 0.2) //7
(0.00218096936826680 0.0499524110790929 0.2) //8
(-0.00218096936826680 0.0499524110790929 0.2) //9
);

blocks
(
hex (0 5 5 0 2 7 6 1) (25 10 5) simpleGrading (1 1 1)
hex (1 3 4 2 6 8 9 7) (15 10 25) simpleGrading (1 1 1)
);

edges
(
arc 2 1 (0 0.001 0)
arc 7 6 (0 0.001 0.2)
arc 4 3 (0 0.05 0)
arc 9 8 (0 0.05 0.2)
);

patches
(
patch
inlet_center_tube
(
(0 2 1 0)
)

patch
outlet
(
(5 7 6 5)
(7 6 8 9)
)

patch
inlet_co_flow
(
(1 2 4 3)
)

wedge
axi_symm-f
(
(0 5 7 2)
(2 7 9 4)
)

wedge
axi_symm-r
(
(0 5 6 1)
(1 6 8 3)
)

wall
wall
(
(4 9 8 3)
)
);

mergePatchPairs
(
);

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

I have checked and the numbering of my patches seems to be correct. I'm doing a one layer thick wedge mesh.

If anyone has any clue or hint, please let me know!

Thanks in advance!

Last edited by DuarteMagalhaes; May 2, 2014 at 06:04.
DuarteMagalhaes is offline   Reply With Quote

Old   April 24, 2014, 11:33
Default
  #2
Senior Member
 
Alexey Matveichev
Join Date: Aug 2011
Location: Nancy, France
Posts: 1,379
Rep Power: 23
alexeym will become famous soon enoughalexeym will become famous soon enough
Hi,

in general this message means you forgot to describe certain patches in blockMeshDict (so face of these patches went to empty patch with the name defaultFaces and checkMesh is not happy about it).
alexeym is offline   Reply With Quote

Old   April 28, 2014, 06:09
Default
  #3
New Member
 
Duarte Magalh„es
Join Date: Apr 2014
Location: Lisbon, Portugal
Posts: 24
Rep Power: 4
DuarteMagalhaes is on a distinguished road
Quote:
Originally Posted by alexeym View Post
Hi,

in general this message means you forgot to describe certain patches in blockMeshDict (so face of these patches went to empty patch with the name defaultFaces and checkMesh is not happy about it).
Hi Alexey,

Indeed, when i run blockMesh, it creates a patch named defaultFaces:
"patch 6 (start: 15700 size: 0) name: defaultFaces". However, this happens because it creates the interface between my two blocks (central tube and annular region), and since it is not a boundary of the main domain, I cannot set this interface as a patch. Do you know how can i define it in blockMeshDict, so that blockMesh knows that it is a simple interface between two blocks?

Thanks for your help!

Last edited by DuarteMagalhaes; April 28, 2014 at 08:14.
DuarteMagalhaes is offline   Reply With Quote

Old   April 28, 2014, 09:00
Default
  #4
Senior Member
 
Alexey Matveichev
Join Date: Aug 2011
Location: Nancy, France
Posts: 1,379
Rep Power: 23
alexeym will become famous soon enoughalexeym will become famous soon enough
Hi,

you should define two patches in these two blocks, and then use mergePatchPairs in blockMeshDict to merger patches. Otherwise you'll have defaultFaces empty type patch between blocks and result won't be as you expect.

Though it's just a guess from what you've written in the previous message. Maybe if you describe the problem in more details someone will be able to propose more convenient way to create a mesh for you case.
alexeym is offline   Reply With Quote

Old   April 28, 2014, 12:48
Default checkMesh error, centre flow + annular flow
  #5
New Member
 
Duarte Magalh„es
Join Date: Apr 2014
Location: Lisbon, Portugal
Posts: 24
Rep Power: 4
DuarteMagalhaes is on a distinguished road
Quote:
Originally Posted by alexeym View Post
Hi,

you should define two patches in these two blocks, and then use mergePatchPairs in blockMeshDict to merger patches. Otherwise you'll have defaultFaces empty type patch between blocks and result won't be as you expect.

Though it's just a guess from what you've written in the previous message. Maybe if you describe the problem in more details someone will be able to propose more convenient way to create a mesh for you case.
Hi,

Thank you for your reply!

I have been reading about face matching and face merging, and apparently OpenFoam says that "To connect two blocks with face matching, the two patches that form the connection should simply be ignored from the patches list. blockMesh then identifies that the faces do not form an external boundary and combines each collocated pair into a single internal faces that connects cells from the two blocks."

This is what i am doing and for this reason he is creating the defaultFaces patch (empty patch).

To describe my problem more thoroughly, I have followed this tutorial: http://www.somogyibence.hu/documents.../Cornell1.html , and afterwards, changed the geometry to insert a central tube, transforming the remaining flow in an annular co-flow.

I do believe the problem is in the interface of these two blocks, centre tube and annular region, however, I am not being able to fix the error that checkMesh reports, which is the following:

"
Checking geometry...
Overall domain bounding box (-0.00218097 0 0) (0.00218097 0.0499524 0.2)
Mesh (non-empty, non-wedge) directions (0 1 1)
Mesh (non-empty) directions (1 1 1)
Wedge axi_symm-f with angle 2.5 degrees
Wedge axi_symm-r with angle 2.5 degrees
***Number of edges not aligned with or perpendicular to non-empty directions: 4160
<<Writing 4186 points on non-aligned edges to set nonAlignedEdges
Boundary openness (-5.30238e-15 -1.60247e-16 6.32555e-19) OK.
Max cell openness = 3.67795e-16 OK.
Max aspect ratio = 400.381 OK.
Minimum face area = 1.74311e-10. Maximum face area = 2.61333e-05. Face area magnitudes OK.
Min volume = 1.39449e-12. Max volume = 1.10163e-08. Total volume = 2.17889e-05. Cell volumes OK.
Mesh non-orthogonality Max: 2.25027 average: 1.10984
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 0.333333 OK.
Coupled point location match (average 0) OK.

Failed 1 mesh checks.

End
"

Can anyone help me on this?
Thanks in advance!
DuarteMagalhaes is offline   Reply With Quote

Old   April 28, 2014, 13:06
Default
  #6
Senior Member
 
Alexey Matveichev
Join Date: Aug 2011
Location: Nancy, France
Posts: 1,379
Rep Power: 23
alexeym will become famous soon enoughalexeym will become famous soon enough
Hi,

checked the tutorial, still can't get what changes did you do to the tutorial mesh. Post your case files, this way it'll be simpler.

Yes, there is face matching algorithm which can merge faces automatically but there are also certain conditions for this algorithm to work.
alexeym is offline   Reply With Quote

Old   April 28, 2014, 14:27
Default
  #7
New Member
 
Duarte Magalh„es
Join Date: Apr 2014
Location: Lisbon, Portugal
Posts: 24
Rep Power: 4
DuarteMagalhaes is on a distinguished road
I am trying to create a domain with inlet: central tube with annular co-flow. In the rest of the domain, this central tube no longer exists, only exists the wall that now contains both the flow entering from the central tube, and the annular co flow.


My blockMeshDict file:

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

convertToMeters 1;

vertices
(

(0 0 0) //0
(0.0000436193873653360 0.000999048221581858 0) //1
(-0.0000436193873653360 0.000999048221581858 0) //2
(0.00218096936826680 0.0499524110790929 0) //3
(-0.00218096936826680 0.0499524110790929 0) //4
(0 0 0.2) //5
(0.0000436193873653360 0.000999048221581858 0.2) //6
(-0.0000436193873653360 0.000999048221581858 0.2) //7
(0.00218096936826680 0.0499524110790929 0.2) //8
(-0.00218096936826680 0.0499524110790929 0.2) //9

);

blocks
(
hex (0 5 5 0 2 7 6 1) (25 10 5) simpleGrading (1 1 1)
hex (1 3 4 2 6 8 9 7) (15 10 25) simpleGrading (1 1 1)
);

edges
(
arc 2 1 (0 0.001 0)
arc 7 6 (0 0.001 0.2)
arc 4 3 (0 0.05 0)
arc 9 8 (0 0.05 0.2)
);

patches
(
patch
inlet_center_tube
(
(0 2 1 0)
)

patch
outlet
(
(5 7 6 5)
(7 6 8 9)
)

patch
inlet_co_flow
(
(1 2 4 3)
)

wedge
axi_symm-f
(
(0 5 7 2)
(2 7 9 4)
)

wedge
axi_symm-r
(
(0 5 6 1)
(1 6 8 3)
)

wall
wall
(
(4 9 8 3)
)
);

mergePatchPairs
(
);

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

My velocity BC's are:

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

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{

inlet_center_tube
{
type fixedValue;
value uniform (0 0 0.7);
}

outlet
{
type zeroGradient;
}

inlet_co_flow
{
type fixedValue;
value uniform (0 0 0.2);
}

wall
{
type fixedValue;
value uniform (0 0 0);
}

axi_symm-f
{
type wedge;
}

axi_symm-r
{
type wedge;
}

}


Thank you so much for your help!
DuarteMagalhaes is offline   Reply With Quote

Old   May 5, 2014, 11:04
Default
  #8
New Member
 
Duarte Magalh„es
Join Date: Apr 2014
Location: Lisbon, Portugal
Posts: 24
Rep Power: 4
DuarteMagalhaes is on a distinguished road
Hi,

I was able to fix the problem by changing my mesh and also by using mergePatchPairs.
Thanks for your help Alexey!
DuarteMagalhaes is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
edges not aligned with or perpendicular to non-empty directions ynos OpenFOAM Native Meshers: blockMesh 5 March 24, 2015 09:15
snappyHexMesh sticking point natty_king OpenFOAM Native Meshers: snappyHexMesh and Others 2 April 17, 2014 01:24
Number of edges not aligned with or perpendicular to non-empty directions am9109 OpenFOAM Native Meshers: blockMesh 0 April 14, 2013 07:33
OF 1.6-ext Number of edges not aligned with or perpendicular to non-empty directions esteban88 OpenFOAM Native Meshers: blockMesh 0 December 21, 2012 04:26
[ICEM] mesh is not aligned with edges OliverL ANSYS Meshing & Geometry 0 November 7, 2011 08:59


All times are GMT -4. The time now is 11:47.