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flywing geometry meshing in GAMBIT

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Old   August 14, 2011, 13:42
Thumbs up flywing geometry meshing in GAMBIT
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hello everyone , cud anyone of u plz suggest me how to do virtual cleanup process for a 3d geometry(Flywing) which was imported frm CATIA file...
can anyone also give me the link where we can find d tutorials for generating mesh around complex 3d geometry like aircrafts so that it would become easy for me to follow up...
please do reply fast and help me , waiting for ur responses...

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Old   August 16, 2011, 16:49
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hello max can u help out in this problem

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Old   August 17, 2011, 00:43
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http://my.fit.edu/itresources/manual...guide/tg05.htm
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Old   August 17, 2011, 04:25
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thanks max for ur reply.
i have already followed these steps but i am still unable to do it, even though there are many faces and edges which are not connected properly as i have imported frm catia file, its not showing/clearing any duplicate faces/edges. after that when i try to heal real faces as its given in the tutorial its showing an error as "the requested operation cannot be performed as the faces 239,238,240...... has upper topology(it exists on volume)".
what does this mean max, how shud i proceed further, i am new to this software and slowly i will try to learn my mistakes if u can help me and i shall be highly thankful to u

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Old   August 17, 2011, 04:34
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typical errors when you are working with virtual entities.
Do you have access to your CAD software for trying to export your geometry with another format (STEP for instance)?
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Old   August 17, 2011, 05:40
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no max i havent worked in CAD software, but still i can take help frm those who knows CAD. so u say to first check d geometry in cad and then try to export to gambit with step file format
could u plz give me ur mail id so that i can contact u directly for any help or add me on vamshi.iare@gmail.com
plz max i am hoping u will add me and reply back to this mssg...
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Old   August 17, 2011, 05:59
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you can continue this thread, maybe it can help somebody else.
Try to ask another format (step or acis).
What kind of file are you importing into Gambit?
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Old   August 17, 2011, 06:19
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ya i am importing .igs file into gambit
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Old   August 17, 2011, 06:41
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no surprise then.
With gambit, iges-imported geometry is automatically converted as virtual, which isn't comfortable, if you wanna do some boolean operations like substract, etc...
My advice: ask step file (or parasolid)
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Old   August 17, 2011, 07:20
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ok can i save the file as .step in CATIA and then try to import and open in GAMBIT
does it show again any virtual edges/faces, i will try this what u have said max
thanks once again...
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Old   September 1, 2011, 12:50
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hello max,
again even after opening d geometry in STEP file format as u have suggested last week its showing the same error "the requested operation cannot be performed as the faces 239,238,240...... has upper topology(it exists on volume)". what does this mean? i am not understanding how to go further
how to get rid of this error max, plz help me out, others can also suggest plz as i am not able to proceed further


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Old   September 2, 2011, 01:21
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can you post the whole error message?
It seems you want to delete any virtual entities
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Old   September 2, 2011, 03:41
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yes i wanted to delete the virtual entities
i tried to follow the procedure from gambit tutorial- Airplane Geometry(chapter 14). these are the following steps i have done till now
1) intially i have imported the geometry using .STEP file format
2) next i have done cleanup of duplicate faces- it was not showing any duplicate edges and the default tolerance value was 0.00885092
3) after that next i have done cleanup of duplicate edges again not showing any duplicate edges
4)i was struck up in this step when i was trying to heal the geometry.i selected all under faces option and unselected smooth faces and applied, then it was showing this error as:
Error: The requested operation cannot be performed because face face.2 has upper topology(it exists on volume)
Error: The requested operation cannot be performed because face face.3 has upper topology(it exists on volume)
Error: The requested operation cannot be performed because face face.4 has upper topology(it exists on volume) .........etc
simillarly i was getting for almost all the faces(total faces are 266).
what should i do to overcome this error?
i can even show my actual geometry which is attached under...

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Old   September 2, 2011, 03:54
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I cannot see your picture

Basically if you import a step file, you get directly a nice real volume.
So no need to clean up you geometry.
Try to keep a real geometry as far as possible, and use merged tool only when you are ready to mesh your geometry.
Why?
If you merge some surfaces (like cleanup tool do), then you have virtual entities. Then if you decide to split your geometry, it will ask more work from you as your geometry were still real.
Typical a real volume split, only needs a plane to be splitted. But a virtual volume needs that the surface which will split the volume belongs to this volume (understand the points of the surface have to belong to edges from volume & the edges of the surface have to belong to surfaces from volume)

So I would reimport your step file, and don't clean up your geometry
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Old   September 3, 2011, 12:07
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thank u max for ur valuable suggestion
I will try to reimport the step file and as u have said i wont clean up my geometry, u mean i shud try to create domain(volume) around the geometry, specify d size functions and try to mesh the whole geometry accordingly.
can i use d symmetry option as my geometry is symmetric so that my workload and computation time can be reduced


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Old   September 3, 2011, 12:47
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Max can u say me if my geometry(body) size is 8500*8400*510 how much can i take for the domain size so that the flow visualization over d body is well captured
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Old   September 5, 2011, 01:46
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If your geometry is symmetric, and your BC are also symmetric. Then you can try with symmetry BC.
There is also the possibiltiy that your physics doesn't allow you to work with symmetry, especially with unsteady phenomenon (for instance von Karman vortex)
Regarding your dimensions, check tutorials, for sure there is one which will you can use.
Even if you think your domain is to short, you may work back in Gambit and extend your domain.
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Old   September 19, 2011, 14:26
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check this link:
http://www.4shared.com/file/XFw8AZ7Q/1_online.html
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