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[GAMBIT] Problems while meshing a 3d CAD model

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Old   January 3, 2013, 02:34
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Maxime Perelli
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it is crashing for a specific operation.
Which one?
>> in your .jou, check the last line (operation)
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Old   January 3, 2013, 04:55
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hi,
while creating faces, its crashing.
Thanks,
Aadhavan
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Old   January 3, 2013, 05:07
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although I am sceptic about creating volume like you are doing, try to create your surface with help other edges.
I assume it is referencing on the surface with 4 red edges in your pdf, so you can try to split the edge opposite to the dark red one (split it in the middle), and create an edge from this midpoint till opposite point (check green edge in picture) Sans titre.png
Then create both surfaces.

In your case I would create airfoils volume. Then your quarter volume (90° rotation).
Then substract this quarter with airfoils >> new volume has hollow in place of airfoils.
Finally do your volume decomposition with splits
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Old   January 3, 2013, 05:25
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hi,
I got what you are saying, thanks for your suggestion, I will do it for next case.
how ever I have done meshing by my approach, but OF takes more time.
for 12 hrs only 60 time step. Now I am running in one processor.

mAx, I have small question to you, what are the basic things we need to check while doing the simulation ( i,e tip speed, torque, pressure raise).
please give me some information.

Thanks,
Aadhavan
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Old   January 3, 2013, 05:40
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-check Mesh
-check convergence
-monitoring any goal
-plausibility of your results (don't hesitate to break computation and check velocity/pressure dustribution)
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Old   January 3, 2013, 05:46
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thanks mAx, I have done check mesh. there is now error and warning message.

I am trying to run in parallel, I will update here.

Thanks,
Aadhavan
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Old   January 5, 2013, 07:50
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Hi mAx and others,
while executing the check mesh, it says:

Checking geometry...
Overall domain bounding box (-2.64119e-16 -2.64893e-16 -3) (0.771296 0.771367 7)

As mentioned before I am using Gambit for meshing. my geometry is quarter of the volume between two cylinders (see the image).

the inner cylinder radius is 0.3072m and outer cylinder radius id 0.771m
-z= 3m and +z = 7 m

I am wondering how can be the bounding box can have this dimension (-2.64119e-16 -2.64893e-16 -3)
is it a problem?

second one:

I ran my simulation for above geometry up to 1500 time step, then I checked the results. The results are totally wrong and the time step continuity error keep on increasing. I am not able to figure out the problem. if I change relTol=0 in fvSolution for p then there is no problem for time step continuity error, but its taking around 10 to 15 min per time step because its taking lot of time to solve p.
please guide me what to do.

please guys, if you are able to spare some time for this case please have a look. I am really dont know what to do.
I have uploaded my case here,
http://www.sendspace.com/file/zcqhmu


Thanks in advance,
Aadhavan
Attached Files
File Type: pdf GeoFig.pdf (35.4 KB, 1 views)
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Old   January 7, 2013, 02:10
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if you are working with OpenFOAM, I would open a new thread in the OpenFOAM subforum. You will have more chance getting replies.
The e-16 are only tolerance "issues", so it is referecing to 0 --> in your case (0 0 -3)
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Old   January 7, 2013, 02:52
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Dear mAx,
Thanks for your reply, I didn’t open new thread, but I found some old thread.
I posted the issue there.

Thanks for your time,
Aadhavan
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