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[GAMBIT] Mesh error while trying to read it using Fluent

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Old   January 4, 2013, 04:47
Default Mesh error while trying to read it using Fluent
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I designed and mesh my combustor chamber using gambit then i tried reading my case with fluent but it fails ,did all i can to remesh or change things but still fails.
This is the error below i got when reading the case.


Loading "C:\Fluent.Inc\fluent6.3.26\lib\fl_s1119.dmp"
Done.


> Reading "C:\Users\dk\Desktop\combustor final 18DEC\combustor with fuel inlet\combustor with fuel inlet.msh"...
102703 nodes.
75 mixed mass-flow-inlet faces, zone 3.
6292 mixed wall faces, zone 4.
17202 mixed wall faces, zone 5.
14044 mixed wall faces, zone 6.
18556 mixed wall faces, zone 7.
272 mixed pressure-outlet faces, zone 8.
126 mixed mass-flow-inlet faces, zone 9.
560306 mixed interior faces, zone 11.
269232 mixed cells, zone 2.

Building...
grid,
Note: Separating wall zone 7 into zones 7 and 1.
wall.3 -> wall.3 (7) and wall.3:001 (1)
Removing 75 unreferenced faces, zone 3.
Cell Centroid is xc 51.793619 yc -0.799997 zc -4.593363
WARNING: no face with given nodes. Thread 2, cell 185542
Error: Build_Grid: grid error.
Clearing partially read grid.

Error: Null Domain Pointer

Error Object: ()
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Old   January 4, 2013, 04:59
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can you post a picture of your geometry?
did you split it? (sounds connectivity problem)
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Old   January 5, 2013, 13:13
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Null pointer means that you have an uncovered face... A volume element at the boundary without an adjacent shell element for Fluent to apply the wall boundary to (or a shell without a line boundary in 2D).

Maybe mAx can tell you how you got that with Gambit (it is easy to make that mistake in ICEM CFD ) Did you delete any shells?
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Old   January 5, 2013, 14:12
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Quote:
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Null pointer means that you have an uncovered face... A volume element at the boundary without an adjacent shell element for Fluent to apply the wall boundary to (or a shell without a line boundary in 2D).

Maybe mAx can tell you how you got that with Gambit (it is easy to make that mistake in ICEM CFD ) Did you delete any shells?
Thank you,YES. The error started when i deleted an earlier swirler then i designed a new modified one which i replaced.
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Old   January 7, 2013, 02:12
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Then the old design may not be deleted properly, and it's surface mesh may remain
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Old   January 7, 2013, 07:42
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Then the old design may not be deleted properly, and it's surface mesh may remain
Thank you Max,did you get the files i sent to you?
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Old   January 7, 2013, 10:44
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Thank you Max,did you get the files i sent to you?
no
private message?
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Old   January 7, 2013, 10:52
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no
private message?
Yes,Max i sent it private maybe i mistakenly sent to a different email,can you kindly confirm your email to me,i wanted to send the cad n mesh files which i still get that error i posted . thanks again
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Old   January 7, 2013, 11:26
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hi, Max i sent .thanks

Last edited by dk_damo; January 7, 2013 at 17:38.
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Old   January 9, 2013, 02:18
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ok not surprised that you get errors in fluent.
you have to restart from beginning. (split problem, connectivity problem and topology problem).
Did you build the geometry in Gambit or did you import anything from cad?
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Old   January 9, 2013, 05:31
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Thanks Max i did it in Gambit
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Old   January 9, 2013, 05:35
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describe shortly how (till you get geometry without any decomposition)
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Old   January 9, 2013, 06:11
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Max what happen was i designed and meshed a swirler and a combustor separately then combined them together i was able to run a case in fluent without a problem then i noticed i needed to modify the swirler with introduction of a boundary called fuel in and this swirler i entirely new from the earlier one then i tried to combine both as i did thats when fluent failed to read it.
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Old   January 9, 2013, 06:26
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Quote:
Originally Posted by dk_damo View Post
i designed and meshed a swirler and a combustor separately then combined them together i was able to run a case in fluent without a problem
I am curious to see the fluent results.
Basically in your model you have an outer box and a swirler, and I can move the swirler anywhere whithout Gambit checked anything.
That means that Gambit treats the outer domain without any hollow , and on the other hand, Gambit has another separate domain: the swirler

From beginning you need to model the outer domain, and also the swirler (but this one as solid). Then substract the outer domain with the solid.
Once it is done, you can go and split.

Do you have a sketch of your model (not gambit)
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Old   January 9, 2013, 07:22
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Hi,Max i sent more info about the problem to your email.thank you very much))
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Old   January 10, 2013, 02:34
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-build the combustion chamber as solid first like page 7 (take care of thickness)
-build the swirler separately as solid and place it to its right place.
Once you assembly is done (as solid), create a bounding box and substract the assembly from the box.
It would extract the fluid domain, and you could start from a clean geometry.
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Old   January 10, 2013, 07:32
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Ok,thank you Max
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