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Converting a 2Dmesh to axisymmetric

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Old   January 14, 2009, 08:07
Default Go to http://openfoam-extend.
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Bernhard Gschaider
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Go to
http://openfoam-extend.svn.sourceforge.net/viewvc/openfoam-extend/trunk/Breeder_ 1.5/utilities/mesh/manipulation/MakeAxialMesh/
and click on "Download GNU Traball"

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Old   January 15, 2009, 07:14
Default Dear Bernhard, Thanks for t
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Dear Bernhard,

Thanks for the makeAxialMesh Utility. I am now able to make a axial mesh in OpenFOAM-1.5.
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Old   January 17, 2009, 09:54
Default Dear Bernhard ! One quick q
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Dear Bernhard !

One quick question, how to specify axis to a grid?
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Old   January 19, 2009, 01:50
Default Dear Bernhard, I am not abl
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Dear Bernhard,

I am not able to use collapseEdges utility, It is giving me segmentation fault....

Can u shed some light on this?

Regards,
Mahendra
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Old   January 19, 2009, 02:26
Default The error i am getting is like
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The error i am getting is like this:

Cell:14998 uses faces:6(29649 30248 60346 60347 29349 29648) of which too many are marked for remov
al:
29649 30248 60346 60347 29349 29648
Cell:14999 uses faces:6(30249 30299 60348 60349 29350 29649) of which too many are marked for remov
al:
30249 30299 60348 60349 29350 29649
Morphing ...
--> FOAM Warning :
From function boundBox::boundBox(const pointField& points)
in file meshes/boundBox/boundBox.C at line 52
Cannot find bounding box for zero sized pointField, returning zero
--> FOAM Warning :
From function boundBox::boundBox(const pointField& points)
in file meshes/boundBox/boundBox.C at line 52
Cannot find bounding box for zero sized pointField, returning zero
Collapsing 0 small edges
Collapsing 0 in line edges
#0 Foam::error::printStack(Foam:stream&) in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOp t/libOpenFOAM.so"
#1 Foam::sigSegv::sigSegvHandler(int) in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/lib OpenFOAM.so"
#2 ?? in "/lib64/libc.so.6"
#3 collapseHighAspectFaces(Foam::polyMesh const&, Foam::PackedList<1> const&, double, double, Foam ::edgeCollapser&) in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/collapseEdg es"
#4 main in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/collapseEdges "
#5 __libc_start_main in "/lib64/libc.so.6"
#6 __gxx_personality_v0 in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/applications/bin/linux64GccDPOpt/coll apseEdges"
Segmentation fault
lcfd@clust5:~/OpenFOAM/lcfd-1.5/Mahendra/Pipe_trial>

Regards,
Mahendra
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Old   January 19, 2009, 12:31
Default Hi Mahendra! The axis is de
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Hi Mahendra!

The axis is defined using the axis-option (it assumes that you have a planar patch of that name). With the offset-option you can move the axis away from that line. I'm not sure what happens if the patch is not planar

@the collapseEdge-crash: no idea. At first try to run checkMesh on your original (axial) mesh to see whether it is valid. It seems to me that the utilitiy is trying to remove too many edges. Decrease the tolerance parameter (what value are you using now?)

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Old   January 20, 2009, 02:53
Default Dear Bernhard, I am using a
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Dear Bernhard,

I am using a edge length as 3m and angle as 5 degree, what i found was when I used edge length as 0.001m, the collapseEdges utility worked fine saying that 0 edges and 0 faces modified.

I assumed that since my pipe length is 3m and wedge angle is 5 degrees I should use them while specifying the arguments to collapseEdges utilty and it resulted in segmentation fault.

Was I correct in using it or not???

Regards,
Mahendra
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Old   January 20, 2009, 13:12
Default Hi Mahendra! The first para
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Hi Mahendra!

The first parameter means "all edges shorter that this will be removed". Which would mean almost all edges. Vary the feature angle

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Old   January 20, 2009, 16:27
Default Hello! I have just learned
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Hello!

I have just learned that my meshes created with makeAxialMesh are not 1 cell but 5 cells thick (in the wedge direction).

Did I do something wrong?
Do you have any idea what may be the problem?

Greetings.
Sebastian.
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Old   January 21, 2009, 16:33
Default Hi Sebastian! Have you chec
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Hi Sebastian!

Have you checked the original (2D planar) mesh? This shouldn't happen unless the original is that thick, too

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Old   January 21, 2009, 17:10
Default Yes I did. The mesh is just
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Yes I did.

The mesh is just fine in both 2D and wedge.
Due to the big amount of cells and their small size this was just my mistake in seeing them correctly.

Sorry.
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Old   January 21, 2009, 17:34
Default Mahendra: Please have a look a
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Mahendra: Please have a look at my post of September 9, 2008: http://www.cfd-online.com/OpenFOAM_D.../126/9114.html

I think your problem is in large differences in sizes of cells/faces in your mesh. Try the modified "collapseEdgesBetter" in my post. Use the option -areaFactor to specify an "areafactor" smaller than the default 1e-9. Maybe 1e-11?

/Ola
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Old   January 21, 2009, 18:07
Default No, that is not the problem.
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No, that is not the problem.
I was just too blind to see them correctly.
But thanks for your advice.!
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Old   January 22, 2009, 00:48
Default Hi Bernhard, Still I am getti
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Hi Bernhard,
Still I am getting the segmentation fault error with using collapseEdgesBetter.

Cell:49999 uses faces:6(100949 100999 201048 201049 97950 98949) of which too many are marked for removal:
100949 100999 201048 201049 97950 98949
Morphing ...
--> FOAM Warning :
From function boundBox::boundBox(const pointField& points)
in file meshes/boundBox/boundBox.C at line 52
Cannot find bounding box for zero sized pointField, returning zero
--> FOAM Warning :
From function boundBox::boundBox(const pointField& points)
in file meshes/boundBox/boundBox.C at line 52
Cannot find bounding box for zero sized pointField, returning zero
Collapsing 0 small edges
Collapsing 0 in line edges
#0 Foam::error::printStack(Foam:stream&) in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigSegv::sigSegvHandler(int) in "/home/lcfd/OpenFOAM/OpenFOAM-1.5/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib64/libc.so.6"
#3 collapseHighAspectFaces(Foam::polyMesh const&, Foam::PackedList<1> const&, double, double, Foam::edgeCollapser&) in "/home/lcfd/OpenFOAM/lcfd-1.5/applications/bin/linux64GccDPOpt/collapseEdgesBett er"
#4 main in "/home/lcfd/OpenFOAM/lcfd-1.5/applications/bin/linux64GccDPOpt/collapseEdgesBett er"
#5 __libc_start_main in "/lib64/libc.so.6"
#6 __gxx_personality_v0 in "/home/lcfd/OpenFOAM/lcfd-1.5/applications/bin/linux64GccDPOpt/collapseEdgesBett er"
Segmentation fault
lcfd@clust5:~/OpenFOAM/lcfd-1.5/Mahendra/Pipe_2D>

Regards,
Mahendra
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Old   January 22, 2009, 11:23
Default Hi Mahendra! Try skipping t
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Hi Mahendra!

Try skipping the collapseEdges-Stuff. Simply set all scalars to zeroGradient and the vectors to slip on the axis-patch (I think that are the settings that work) and try to use the mesh that way

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Old   February 6, 2009, 06:35
Default Hi, I have created a 3D mes
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Hi,

I have created a 3D mesh with Gmsh, 1 element thick, and used gmshToFoam to convert it. checkMesh gave an "OK"

Now I want to use makeAxialMesh to convert my mesh into an axi-symmetrical one. This was the result:

Create time

Create mesh for time = 0

Plane of the grid: (0 0 1) (0.105253 0.0174027 0.0005)

The rotation-axis: ((-0.06 0 0.0005) (0.94 0 0.0005))

Creating wedge with an opening angel of 5 degrees

Radius to axis: min = 1.0842e-19 max 0.05
#0 Foam::error::printStack(Foam:stream&) in "/home/age/OpenFoam/OpenFOAM-1.5/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigSegv::sigSegvHandler(int) in "/home/age/OpenFOAM/OpenFOAM-1.5/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted: [0xb7ff3400]
#3 getDistance(Foam::polyPatch const&, Foam::line<foam::vector<double>, Foam::Vector<double> >&) in "/home/age/OpenFOAM/age-1.5/applications/bin/linuxGccDPOpt/makeAxialMesh"
#4 main in "/home/age/OpenFOAM/age-1.5/applications/bin/linuxGccDPOpt/makeAxialMesh"
#5 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#6 _start in "/home/age/OpenFOAM/age-1.5/applications/bin/linuxGccDPOpt/makeAxialMesh"
Segmentation fault

What did I do wrong?

FYI, I'm not only an OpenFoam newby, but also a Linux newby, so please explain the whole process step by step.
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Old   February 6, 2009, 09:30
Default Hello, i suppose you have f
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Hello,

i suppose you have followed the wiki instructions and checked the different constraints : http://openfoamwiki.net/index.php/Contrib_MakeAxialMesh

As you have already your model in gmsh, you can directly revolve your mesh in gmsh :

- rotate -2.5° your plane from your main 2D plane
- extrude (revolve) 5°
- save mesh
- gmshToFoam

I've already done that with gmsh, it works fine.

You can also have another solution by revolving your mesh in OpenFoam with the extrudeMesh tool, but it's not the easier way to do, i think.

Good luck.
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Old   February 6, 2009, 09:35
Default Hi Age! No idea (havn't see
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Hi Age!

No idea (havn't seen that stacktrace). How big is the mesh? Could you pass the mesh to me and I'll have a look

Bernhard
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Old   February 6, 2009, 10:49
Default @ Etienne: So you don't use m
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@ Etienne:
So you don't use makeAxialMesh at all? Just extrude using rotation in Gmsh?

@ Bernhard:
The mesh-file is very large. I will try some other things first, like simple geo's etc.

Thanks guys
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Old   February 6, 2009, 11:52
Default It depends on the case, if my
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It depends on the case, if my geometry is done in gmsh, i revolve the mesh in gmsh. If i already have a mesh in gambit or a blockMeshDict, i use makeAxialMesh.

All those procedures should work, i've tried successfully many different ways to build axy cases in OpenFOAM.

If your msh file is too large, perhaps you can zip the .geo, it should be easier to transfer.
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