CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > ANSYS Meshing & Geometry

[GAMBIT] Stairstep meshing in Gambit

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   June 9, 2011, 07:27
Default Stairstep meshing in Gambit
  #1
New Member
 
Ivan
Join Date: Sep 2010
Location: Russia , Moscow.
Posts: 13
Rep Power: 6
Zato_Ichi is on a distinguished road
Hello !

I have a quiet simple geometry, but i cannot find the way how to mesh it with stairstep type. There is a pipe (H=0.5, R=0.01) and rectangular hexahedron (W=0.5 D=0.3 H=0.3), and i want to mesh the pipe with stairstep, but i don't know how to connect them back after that. Than i'm trying to mesh both pipe and hexahedron with required precision (Interval size 0.001) it cannot satisfy memory request. So i need to refine mesh in hexahedron, but idon't know how. Stairstep meshing is necessarily in my case because pipe has a complex shape with corners and curves in general.

Thank you for help!
Attached Images
File Type: jpg geometry.jpg (18.5 KB, 59 views)
Zato_Ichi is offline   Reply With Quote

Old   June 9, 2011, 10:18
Default
  #2
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
I am not familiar with stairstep (never used), but do you want only stairstep mesh because of your solver or whatever?
Or do you want staistep because you think this is the only wayto mesh your stuff with hexa?
Ca you display your pipe with complex shape?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   June 9, 2011, 14:55
Default
  #3
New Member
 
Ivan
Join Date: Sep 2010
Location: Russia , Moscow.
Posts: 13
Rep Power: 6
Zato_Ichi is on a distinguished road
Well, it should be something like that. Worse than pipe has \Omega - like shape, but i haven't even tried to make it. In case shown on pic leads of pipe could be meshed with cooper scheme, but middles meshes only with tetrahedra cells. I'm investigating shockwaves propagation in pipe and following jet simulation, so i need mesh as symmetrical as possible as asymetric influences on jet.
Attached Images
File Type: jpg P_pipe.jpg (13.9 KB, 38 views)
Zato_Ichi is offline   Reply With Quote

Old   June 10, 2011, 01:49
Default
  #4
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
If you decompose your domain you won't have any problem to mesh it with hex or cooper.
Just split before and after elbows.
Then if you want symmetric mesh, you can work with one half of your domain (symmetry), mesh it and once your grid is ready, you can reflect your domain (with mesh)
You get the whole domain with reflected grid from symmetry (>> symmetric grid)
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   June 10, 2011, 05:57
Default
  #5
New Member
 
Ivan
Join Date: Sep 2010
Location: Russia , Moscow.
Posts: 13
Rep Power: 6
Zato_Ichi is on a distinguished road
Thank you very much for your replies !

I made decomposition as you recommended, now direct parts are meshing with hex, but elbow not. Maybe i made something wrong ? While meshing Cooper error appears : regular side face (s) mesh for projecting volume could not found.

About symmetry, actually i need it about the pipe axis to avoid asymmetry on the pipe output.. so pave scheme is not good too, but it is only scheme that can mesh endings with hex. I made boundary condition on the end and it seems that it could not be meshed symmetrically with hex.


Best regards !
Attached Images
File Type: jpg elbow.jpg (20.7 KB, 30 views)
File Type: jpg lead.jpg (33.9 KB, 39 views)
Zato_Ichi is offline   Reply With Quote

Old   June 10, 2011, 06:56
Default
  #6
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
From your first picture you can see 3 edges . From here it seemed you generated a local axis-system.
So split elbow with surfaces made from edges. Elbow will be splitted into 3 subvolumes.
Then check this tutorial: http://my.fit.edu/itresources/manual...guide/tg03.htm
Remember you have to mesh first the elbow and then the other volumes (because of projection)
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 06:31
Default
  #7
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
i found that the stairstep meshing is rather strange.
it creates a new boundary for me and also the result is not good.

any suggestions please.

my interval size was 12 and Hex and stairstep.
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 07:36
Default
  #8
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
pictures may help
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 08:53
Default
  #9
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
DEAR Max,

thanks for replying. i had not proceeded with the stairstep as a repeat of my buildings and domain have been done they were called f_285 etcc. this had been automatically generated as soon as i apply stairstep function..

can you please elaborate on the use of this function?
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 08:59
Default
  #10
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
why do you want to use stairstep?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 09:01
Default
  #11
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
because no other option is meshing my domain and building..
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 09:05
Default
  #12
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
May I see how your geometry looks like?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 09:40
Default
  #13
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
hi this is my domain and you can see two has been generated.
Attached Images
File Type: jpg error.jpg (97.6 KB, 26 views)
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 09:58
Default
  #14
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
I meant the buildings...
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 10:02
Default
  #15
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
i do not have it on my pc right now as all my work is done at the university..

i had only this one which i had meshed with stairstep.
you can clearly see another domain has been generated..
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 10:05
Default
  #16
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
yes I see it, but it is stairstep.
For sure you can mesh it with combination of tetra/hexcore and size-function.
But also for sure, you cannot mesh on the fly, and you will have to prepare your geometry
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 10:07
Default
  #17
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
yes i understand.
but i have already tried all combinations only Hex and Staircase works..
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 10:10
Default
  #18
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
did you split your volume?
did you merge some surfaces for deleting sharp edges?
did you apply size function on small entities for preventing cell skewness?
etc...
etc...
And finally did you read error messages from gambit?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Old   November 14, 2012, 10:26
Default
  #19
Senior Member
 
zaynah K.
Join Date: Jun 2012
Location: Mauritius
Posts: 138
Rep Power: 5
zaynah04 is on a distinguished road
error message from gambit was that high skewness...

and i did most of the above.
zaynah04 is offline   Reply With Quote

Old   November 14, 2012, 10:29
Default
  #20
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,961
Rep Power: 30
-mAx- will become famous soon enough
If you want you can provide me the dbs file
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is online now   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[ANSYS Meshing] ANSYS Meshing vs GAMBIT aerospain ANSYS Meshing & Geometry 0 September 28, 2011 06:05
Gambit meshing error jx FLUENT 11 May 26, 2009 10:35
GAMBIT problem with 3D Boundary Layer when meshing Anthony Haroutunian FLUENT 2 March 26, 2008 03:02
meshing a fan using gambit tony FLUENT 1 February 15, 2008 01:28
Gambit: too long meshing time! delsolman FLUENT 1 January 29, 2008 20:06


All times are GMT -4. The time now is 09:47.