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-   -   System error during meshing (http://www.cfd-online.com/Forums/openfoam-meshing-open/61957-system-error-during-meshing.html)

ares_tum October 11, 2006 04:48

I got a very complicated geome
 
I got a very complicated geometry (no warning or error when imported by netgen), which is being meshed by netgen now. The meshing takes at least 2 hours, but still around 99.8%. It shows in the command window that:
"System error: hash table si not fitting for segment: ..."
Does anyone know what's the problem?
Thanks in advance.

hjasak October 11, 2006 04:51

sounds like you ran out of mem
 
sounds like you ran out of memory: this must be a pretty big mesh!

Hrv

ares_tum October 11, 2006 05:03

This is the model.
 

This is the model.

ares_tum October 11, 2006 05:06

Here is the model, could anyon
 
Here is the model, could anyone try to mesh it?
Thanks
http://www.cfd-online.com/OpenFOAM_D...s/mime_zip.gif stl.zip

christian_hausmann October 11, 2006 06:53

There are a lot of intersectin
 
There are a lot of intersecting elements in your model.

Can you change the settings of you CAD program to get a better stl-file?

Netgen needs a almost perfect geometry to finish meshing.

ares_tum October 11, 2006 07:10

Thanks for your answer,Christi
 
Thanks for your answer,Christian.
The original model is downloaded from internet. I just cut one part out, and added a top onto it.
Could you please tell me where do the intersecting elements locate? On the top, bottom,or lateral surface? How to solve it?cad?
Thanks

christian_hausmann October 11, 2006 07:48

They are spread over the hole
 
They are spread over the hole surface. Use a CAD program. Try to vary the features of the stl-export-function. (more accuracy) What's you CAD program?

ares_tum October 11, 2006 08:25

I think i can see them now in
 
I think i can see them now in netgen. Really a lot. I am not familiar with cad and don't have any cad program in my computer. Are there any other possibilities? Or i have to modify them by handhttp://www.cfd-online.com/OpenFOAM_D...lipart/sad.gif
Thanks a lot.

christian_hausmann October 12, 2006 03:18

You can try to use the stl-doc
 
You can try to use the stl-doctor.

Change "Double Click selects:" to "triangle" and select one blue-edged triangle, or Deselect "select with mouse", Insert the number of an intersecting triangle below.

After selecting an intersecting triangle use "move point to middle of trianglepoints". Maybe 0-volume-triangles were generated, delete them. Save the geometry.

Be sure that you exclusively insert the number of an intersecting element. Select an triangle with mouse is not always as easy as it seems.

ares_tum October 12, 2006 04:14

Great thanks, Christian. I'll
 
Great thanks, Christian. I'll try it.

philippose October 30, 2006 14:37

Hi Zhengxiong, I had a look
 
Hi Zhengxiong,
I had a look at your STL file in Netgen, and tried a moderate mesh generation... Here is a screen-shot of the result I got... I have marked in red the areas (there are more on the rear side), where Netgen is having trouble closing the mesh due to inconsistent and intersecting triangles....

As Christian Hausmann suggested, I think you need an STL export with finer triangles defining the surface....



Philippose

philippose October 30, 2006 14:40

Oops.... Looks like the file d
 
Oops.... Looks like the file didnt get uploaded... second try :-)

http://www.cfd-online.com/OpenFOAM_D...your_image.gif

Philippose

philippose October 30, 2006 14:45

Looks like Firefox in Linux fo
 
Looks like Firefox in Linux for some reason doesnt support this possibility of uploading files.... any suggestions from anyone ??

Sorry for flooding the message board :-)!

Philippose

mattijs October 31, 2006 13:56

Hi Philippose, Just a test
 
Hi Philippose,

Just a test to see if the uploading works from konqueror. You are aware of the 50k limit?

http://www.cfd-online.com/OpenFOAM_D...s/mime_txt.gif unitCube.stl

philippose October 31, 2006 14:55

Hi, 50k limit :-)!! Oh my...
 
Hi,
50k limit :-)!! Oh my... no wonder... its all clear now :-)! The image was 450Kb... but well, with some Gimping and rescaling, I have it down to 12.5Kb... lets see if it works now :-)!

http://www.cfd-online.com/OpenFOAM_D...your_image.gif


Thanks for pointing out the limit Mattijs :-)!

Philippose


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