CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

Boundrycondition problem between Gambit and Fluent

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 29, 2006, 05:21
Default Boundrycondition problem between Gambit and Fluent
  #1
smalawi
Guest
 
Posts: n/a
Hi all,

i'm working with a freind on modeling a premixed burner in Gambit. So far we gnenrated the mesh in Gambit and specified the boundry conditions.

the burner has to inlets, one for fuel gas which is velocity spec and the other is for air and was set to pressure inlet in gambit. there is also a combined outlet, which is set to pressure outlet. in both caese we specified the faces for the boundry type with no problems.

after exproting the mesh in Fluent, we can olny see the wall, interior and outlet. the fuel inlet and air are both messing.

what is the problem here? how to fix it?

I'm used on solving only 2D problems and never had this issue before, my freind has no clue?

cheers,

sm
  Reply With Quote

Old   October 30, 2006, 09:07
Default Re: Boundrycondition problem between Gambit and Fl
  #2
Jason
Guest
 
Posts: n/a
It sounds like the faces you defined BCs on weren't part of the meshed volume. Check your connectivity. Another common reason is that there are two volumes (one being a copy of the other)... and when you meshed, Gambit picked the first volume, but when you went to define your BCs, Gambit picked the second volume... The next common problem is that surfaces picked for inlets were already picked as walls... I believe Gambit leaves the first BC that was assigned and ignores the second.

Check those things first, and if you can't find the problem, then post more information about your problem (like how you built the geometry).

Hope this helps, and good luck, Jason
  Reply With Quote

Old   October 30, 2006, 22:52
Default Re: Boundrycondition problem between Gambit and Fl
  #3
smalawi
Guest
 
Posts: n/a
Thanks Jason for the tips,

I checked the volumes and I only have one. I used the tri mesh for meshing the volume directly without any other adjustments. I deleted the boundary conditions and reworked them so that I select the faces I want by name and cross checking any overlap, there was non.

I exported the mesh to fluent and still had the same problem; both inlet boundary conditions were not visible. Only interior, wall (or new wall), and the outlet, I suspect that fluent is combining the other boundaries with the wall and renaming them new wall. I do not know how to fix this. Can you think of something?

i created the volume as follows:

1. Created vertices in gambit to generate the 2D face, which I used later on without problems. 2. meshed the 2D face and created the boundary conditions 3. saved the file. 4. removed the old mesh 5. Created the 3D volume by rotating the 2D mesh around the x axis (360 deg). 6. meshed the volume directly with tri mesh 7. Removed the old boundary conditions and created new ones for the new faces 8. exported the mesh to fluent and it looks good except for the boundary conditions?

Appreciate any help that I can get on this issue. I tried with my friend to create another 3D model to verify the software, basically a cylinder tube directly and used it in fluent without problems?

  Reply With Quote

Old   October 31, 2006, 13:21
Default Re: Boundrycondition problem between Gambit and Fl
  #4
Nikhil
Guest
 
Posts: n/a
even i am having similar types of problems i cant find the the boundary conditions that i applied in gambit in Fluent. i think there might be an easier way to get around this problem. will really appreciate if somebody can give some tips to get around this problem.

Thanks in advance for the response Nikhil
  Reply With Quote

Old   October 31, 2006, 15:57
Default Re: Boundrycondition problem between Gambit and Fl
  #5
Jason
Guest
 
Posts: n/a
Under solver, make sure Fluent 5/6 is selected before defining BCs. Other than that, the only thing I can think of is to start from scratch (instead of starting from the 2D geometry). There may be something weird still attached to some of the geometry... even though you delete the BCs Gambit might not realize it when you switch from 2D BCs to 3D BCs. The face may still think it has a "fluid volume" BC attached to it when from when it exported the 2D mesh... or one of the edges may still think it's a wall or something.

You might want to support a ticket to your Fluent support too (if you're able to... I know sometimes having access to Fluent support is difficult if you're in a university)... this could be a bug and they may or may not have a fix for it.

Hope this helps, and good luck, Jason
  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
Fluent 6.3 / Gambit 2.3.16 / Exceed 11 problem on Win7 pdilly FLUENT 19 April 2, 2013 04:17
Fluent simulation problem & Gambit "database"error Chase Estrin FLUENT 4 February 21, 2013 05:15
problem gambit and fluent non premixed combustion LES ex-bmx FLUENT 0 April 23, 2010 18:24
Gambit and fluent problem Rezassp FLUENT 2 November 2, 2004 05:59
Gambit Meshing export to fluent minor problem John c. FLUENT 2 February 6, 2002 17:52


All times are GMT -4. The time now is 23:35.