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Streamlines in 3d geometry

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Old   January 23, 2008, 11:03
Default Hi, I'm just beginning with O
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Manuel Larenas Aravena
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Hi,
I'm just beginning with OpenFoam and I've been working on a 3d mesh. As it says in the UserGuide, you have to extract the Internal Mesh to plot the streamlines... but I need to plot them through the entire 3d geometry! is there a way to perform this?

I would really appreciate any help

Manuel
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Old   June 2, 2008, 18:34
Default Hi I can plot streamlines i
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Alexandre Pereira
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Hi

I can plot streamlines in an extracted mesh in ParaFoam ( Paraview 2.4.4 ). I am using OpenFOAM 1.4.1, the issue is that some of the streamlines break in a nonphysical fashion... they just get interrupted, it happens with large cases 2.5 M cells,
i am running OF in Ubuntu 7.10 w/ 2GB memory and an ATI Radeon Mobility x2300...

Is there any form of fixing this ( besides the obvious one of running a smaller case... :-) ) ?

It it some kind of bug already fixed in Paraview 3.x, or is it OS specific...?

Thanks in advance

Alex
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Old   June 2, 2008, 20:01
Default Hi Alexandre, Does your mesh
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Takuya OSHIMA
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Hi Alexandre,
Does your mesh contain polyhedral (incl. split-hex) cells? If that's the case try foamToVTK instead of directly reading your case with paraFoam. foamToVTK does a better job in decomposing polyhedral cells than paraFoam's on-the-fly decomposer, which largely affects the behavior of the streamline filter.

Takuya
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Old   June 3, 2008, 10:00
Default Hi Oshima Takuya, Thanks fo
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Alexandre Pereira
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Hi Oshima Takuya,

Thanks for your fast answer. I can do that allrignt :
foamToVTK . mycase -ascii -allPatches -fields "(U p k epsilon phi)" -time 3.2

as an example, but the issue is that i do not know how to manipulate the VTK database, extract its features, etc...

In paraFoam environment i would simply extract the internal mesh, extract one or several patches ( an airplane surface for instance ) colour that patch by pressure. apply an isosurface operator to that patch so as to explicit the isopressure lines over that surface ( in a healthy design they should be as orthogonal to the direction of flow as possible, any departure from that condition will mean that there may be conditions for pressure gradient reversal... bad news...), and apply the streamline operator to the internal mesh...

... just as easy as that... with a VTK database... well ... :-(

How do i extract a patch ? ( a car or an airplane surface... )... ?

Can i apply operators as simply as do it in an OpenFOAM database...?

Somehow the "extract parts" feature is not active in the "filter" scroll down menu...

... wy whole querying ability gets compromised...

...How do i do it...?

Alex
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Old   June 3, 2008, 19:53
Default Hi Alex, You could try to run
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Takuya OSHIMA
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Hi Alex,
You could try to run foamToVTK again with -allPatches removed from your command line, and read *.vtk files for each patch created under VTK/<patchname> directory.

Takuya
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Old   June 4, 2008, 17:38
Default Hi OSHIMA Takuya Thanks onc
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Alexandre Pereira
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Hi OSHIMA Takuya

Thanks once more,

I did as you told and no way... i cannot extract inner boundaries in my cfd domain...

It may be possible, but i do not know how to do it with VTK format...

Anyway, i built streamlines from my Vtk database... changed its visibility so that only the streamlines would be visible, and tha same thing happens... lots of streamlines broken for no apparent reason...

Happens in a vtk database in paraview 2.4.4 and paraview 3.2.1.

On the other hand, if i choose an Ensight data export and open it in Ensight 8.2.2 Gold, the streamlines are there allright... not randomly broken...

My problem is that my trial license of EnSight is almost expiring... and i am running short of options... :

MayaVi won't open VTK databases in unstructured format like paraview does... if it wasn't for the cranked streamlines... :-(

Thanks anyway...

Regards

Alex
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Old   June 6, 2008, 10:47
Default Hi Again Oshima. I have sol
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Alexandre Pereira
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Hi Again Oshima.

I have solved my difficulty in VTK manipulation...

The patches are all located in another folder inside the main VTK database folder... from there i can select whichever patch i need to open, and post it in Paraview... no need to extract features like in a Foam database...

BTW, do you happen to know when will Paraview 2.4.4 be superseeded by paraview 3.x as a default OpenFOAM viewer...?

Best regards

Alex
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Old   June 6, 2008, 11:08
Default Hi, @3.x migration: I (or all
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Takuya OSHIMA
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Hi,
@3.x migration: I (or all the community?) believe we don't have to wait so long before it happens [1].

[1] http://www.opencfd.co.uk/openfoam/version1.5beta.html

Takuya
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Old   June 9, 2008, 21:06
Default Hi Oshima, One more questio
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Alexandre Pereira
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Hi Oshima,

One more question... is there any way to import EnSight format into Paraview without the *%&"#)? "core dump"...?

Should i import it in "Little Endian" or "Big Endian" Format...?

As far i I can recall, Paraview 2.4.4. won't allow it,... Paraview 3.2.1 won't either...

is there some kind of "trick" to be used in foamToEnsight? or it is just the way things are, not being able to use Paraview with EnSight Format...?

Best regards

Alex
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Old   June 9, 2008, 21:51
Default Hi Alex, I have almost no e
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Takuya OSHIMA
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Hi Alex,

I have almost no experience with foamToEnsight so I guess you could ask Mark in another thread [1], especially if you are interested in its polyhedra handling.

[1]http://www.cfd-online.com/OpenFOAM_D...tml?1212995919

Takuya
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