[GAMBIT] 3D Mesh for complex structure

Shinobi · November 16, 2012, 10:16

Quote:

Originally Posted by -mAx-

create one and use move tool to reach interested area...

Ok perfect!!
Now I must complete all model.
Anyway all this new volumes are connected, really?
So I mesh and no problem with solution in fluent?

-mAx- · November 16, 2012, 10:22

yes they are connected.
To be sure, try to pick a volume and move it anywhere.
If you can move it, then it is not connected.
If you cannot, Gambit gives you the reason: connected to another entity...

Shinobi · November 16, 2012, 10:28

Quote:

Originally Posted by -mAx-

yes they are connected.
To be sure, try to pick a volume and move it anywhere.
If you can move it, then it is not connected.
If you cannot, Gambit gives you the reason: connected to another entity...

Very good trick!

Shinobi · November 16, 2012, 10:39

Quote:

Originally Posted by -mAx-

yes they are connected.
To be sure, try to pick a volume and move it anywhere.
If you can move it, then it is not connected.
If you cannot, Gambit gives you the reason: connected to another entity...

WAIT.
I rotate a volume:
no error message, GAMBIT rotate all model.
Also if I translate: GAMBIT translate all model.
Is it normal?

-mAx- · November 16, 2012, 10:46

yes it is if you enable "connected geometry" --> it means, Gambit moves also all entities which are connected to the one you moved
Then the trick works if you disable the option

Shinobi · November 16, 2012, 11:20

Ok all clear!
But I have a problem now.
When I mesh blue volume, GAMBIT consiglia me HEX/Wedge.
But I have this error:

ERROR: Projection intersection attempted without any free nodes on the
intersecting edge. Volume volume.25 could not be meshed.

When I mesh with TET/Hybrid:

Mesh of face face.778 contains 1 highly skewed elements (EQUISIZE SKEW > 0.97).

Mesh of face face.752 contains 1 highly skewed elements (EQUISIZE SKEW > 0.97).
ERROR: Meshing volume volume.25 aborted due to poor face mesh quality.
The user may proceed by first remeshing the faces with poor mesh quality,
or attempt to mesh the volume with the existing face meshes.
ERROR: Volume volume.25 could not be meshed without face(s) successfully meshed.

-mAx- · November 16, 2012, 14:10

the blue volume has to be meshed with tetra.
If you want hexa, then you have to find a good decomposition.
The skewness is due a very small edge.
Here you can apply a size function for meshing finer in this area.
Or you modify your cad for preventing this issue

-mAx- · November 19, 2012, 02:36

The very small edge issue can be fixed, by splitting the blue region with a surface formed by 4 vertices (small edges)
Sans titre1.png Sans titre2.png
Then you can mesh without errors and skewness problem

Shinobi · November 29, 2012, 19:34

Hi max,
I send you a new part of model.
Problem is how connect all volumes.
I cannot connect external volume (half fuselage).
Have you some other trick?
thanks for your help!

-mAx- · November 30, 2012, 03:31

did you try to merge alöl parts in your cad package?
in Gambit it will be tough

Shinobi · November 30, 2012, 03:45

Quote:

Originally Posted by -mAx-

did you try to merge alöl parts in your cad package?
in Gambit it will be tough

I don't know..
You say in the program that created it, or another application?
I have this model, when I import it, I have 87 ACIS BODY, 672 FACES, 23 EDGES, 0 VERTEX. So it does not recognize all volumes, only 87. I must connect faces with sticht command to create them.
But after I have problem with connections.

-mAx- · November 30, 2012, 03:58

yes the program which creates the the model

Shinobi · November 30, 2012, 04:06

Quote:

Originally Posted by -mAx-

yes the program which creates the the model

then I cannot do anything in GAMBIT?

Shinobi · November 30, 2012, 04:24

Another question:
it may be due to poor tolerance of model saved in CAD package?
When I import it, I have distance tolerance of 0.001: it is too low?

-mAx- · November 30, 2012, 07:06

I don't know...
which cad pakage are you using?

Shinobi · December 3, 2012, 08:03

Quote:

Originally Posted by -mAx-

I don't know...
which cad pakage are you using?

My cad pakage is Catia.

-mAx- · December 4, 2012, 03:02

I don't knw this package, but check if you have the possbility to merge all volumes (parts) into one (like a fusion)

Shinobi · December 4, 2012, 05:07

Quote:

Originally Posted by -mAx-

I don't knw this package, but check if you have the possbility to merge all volumes (parts) into one (like a fusion)

ok I'll try, but this operation it will not be quick because I don't have to hand the source at the time.
Anyway can you advise me importing options?
Just to see if there are errors or trips to use.

-mAx- · December 4, 2012, 05:13

i am handling with step files...
Else you can delete all you volumes (without otion lower geometry), and reconstruct the whole volume.
But you need to split and connect many surface.
It will ask you lots of work...

Shinobi · December 4, 2012, 05:29

Quote:

Originally Posted by -mAx-

i am handling with step files...
Else you can delete all you volumes (without otion lower geometry), and reconstruct the whole volume.
But you need to split and connect many surface.
It will ask you lots of work...

It is the same thing if I import model without make tolerant so I have only faces?

November 16, 2012, 10:22		#22
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	yes they are connected. To be sure, try to pick a volume and move it anywhere. If you can move it, then it is not connected. If you cannot, Gambit gives you the reason: connected to another entity... Shinobi likes this. __________________ In memory of my friend Hervé: CFD engineer & freerider

November 16, 2012, 10:46		#25
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	yes it is if you enable "connected geometry" --> it means, Gambit moves also all entities which are connected to the one you moved Then the trick works if you disable the option __________________ In memory of my friend Hervé: CFD engineer & freerider

November 16, 2012, 14:10		#27
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	the blue volume has to be meshed with tetra. If you want hexa, then you have to find a good decomposition. The skewness is due a very small edge. Here you can apply a size function for meshing finer in this area. Or you modify your cad for preventing this issue __________________ In memory of my friend Hervé: CFD engineer & freerider

November 19, 2012, 02:36		#28
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	The very small edge issue can be fixed, by splitting the blue region with a surface formed by 4 vertices (small edges) Sans titre1.png Sans titre2.png Then you can mesh without errors and skewness problem __________________ In memory of my friend Hervé: CFD engineer & freerider

November 30, 2012, 03:31		#30
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	did you try to merge alöl parts in your cad package? in Gambit it will be tough __________________ In memory of my friend Hervé: CFD engineer & freerider

November 16, 2012, 11:20		#26
Shinobi Member Join Date: Oct 2012 Posts: 44 Rep Power: 14	Ok all clear! But I have a problem now. When I mesh blue volume, GAMBIT consiglia me HEX/Wedge. But I have this error: ERROR: Projection intersection attempted without any free nodes on the intersecting edge. Volume volume.25 could not be meshed. When I mesh with TET/Hybrid: Mesh of face face.778 contains 1 highly skewed elements (EQUISIZE SKEW > 0.97). Mesh of face face.752 contains 1 highly skewed elements (EQUISIZE SKEW > 0.97). ERROR: Meshing volume volume.25 aborted due to poor face mesh quality. The user may proceed by first remeshing the faces with poor mesh quality, or attempt to mesh the volume with the existing face meshes. ERROR: Volume volume.25 could not be meshed without face(s) successfully meshed.

November 29, 2012, 19:34		#29
Shinobi Member Join Date: Oct 2012 Posts: 44 Rep Power: 14	Hi max, I send you a new part of model. Problem is how connect all volumes. I cannot connect external volume (half fuselage). Have you some other trick? thanks for your help!

November 30, 2012, 03:58		#32
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	yes the program which creates the the model __________________ In memory of my friend Hervé: CFD engineer & freerider

November 30, 2012, 04:24		#34
Shinobi Member Join Date: Oct 2012 Posts: 44 Rep Power: 14	Another question: it may be due to poor tolerance of model saved in CAD package? When I import it, I have distance tolerance of 0.001: it is too low?

November 30, 2012, 07:06		#35
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	I don't know... which cad pakage are you using? __________________ In memory of my friend Hervé: CFD engineer & freerider

December 4, 2012, 03:02		#37
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	I don't knw this package, but check if you have the possbility to merge all volumes (parts) into one (like a fusion) __________________ In memory of my friend Hervé: CFD engineer & freerider

December 4, 2012, 05:13		#39
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	i am handling with step files... Else you can delete all you volumes (without otion lower geometry), and reconstruct the whole volume. But you need to split and connect many surface. It will ask you lots of work... __________________ In memory of my friend Hervé: CFD engineer & freerider

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[snappyHexMesh] Layers:problem with curvature	giulio.topazio	OpenFOAM Meshing & Mesh Conversion	10	August 22, 2012 10:03
[snappyHexMesh] snappyHexMesh won't work - zeros everywhere!	sc298	OpenFOAM Meshing & Mesh Conversion	2	March 27, 2011 22:11
[snappyHexMesh] external flow with snappyHexMesh	chelvistero	OpenFOAM Meshing & Mesh Conversion	11	January 15, 2010 20:43
Icemcfd 11: Loss of mesh from surface mesh option?	Joe	CFX	2	March 26, 2007 19:10
mesh data structure for zone connectivity	Xiaoming	Main CFD Forum	0	March 7, 2005 16:33