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

[GAMBIT] different boundary condition on one volume face

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 29, 2009, 12:56
Default different boundary condition on one volume face
  #1
New Member
 
Slawek Mikula
Join Date: Mar 2009
Posts: 5
Rep Power: 8
slawek.mikula is on a distinguished road
Hello,

I'm struggling with the Gambit software. I was looking for the correct answer in the forum, but i think i am looking for the wrong keywords. I would be greatly appreciated for a help.

Problem:
I am modeling a vlsi chip for a thermal simulation. The chip surface is divided in many functional modules. I would like to define different boundary condition for an each area of one volume face (top) in order to define independent heat flux condition for each "module" on the chip. I cannot model it as above.

What i am doing:
- create bottom volume
- create functional module's volumes and place them on top of the bottom volume with no space between vertical faces of the modules
- create a "unite" method on all above volumes
- ... error (this creates one volume without many faces on the top of the chip)

I am doing "unite" on the volumes in order to spread temperature during simulation.

What steps should I take in order to model it correctly? Should I create inner boundary condition for each bottom-module pair and for all module-module pair ? Or there is another way ? Thanks in advance.
slawek.mikula is offline   Reply With Quote

Old   March 29, 2009, 14:39
Default
  #2
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,992
Rep Power: 30
-mAx- will become famous soon enough
post a sketch of your issue, for a good understanding.
Your problem right now is just the modelling, not the BC, right?
-mAx- is offline   Reply With Quote

Old   March 29, 2009, 17:20
Default
  #3
New Member
 
Slawek Mikula
Join Date: Mar 2009
Posts: 5
Rep Power: 8
slawek.mikula is on a distinguished road
I've attached example file. I've got volume - 'surface' and three "modules" r_a, r_b, r_c. I would like to create in fluent heat flux for the three "modules" independently eg. face.13 will be 'wall' boundary condition and in fluent i'll attach heat flux (transient thermal analysis).

In order to transfer heat to the other volumes earlier i had "unite real volumes" but in previous models i haven't got "modules" that close to each other. When I apply "unite" right now all modules r_a, r_b, r_c are combined together and there is only one "top" face.

Maybe i should model it other way. But what kind of inner boundary condition apply to the faces between modules in order to allow bidirectional heat transfer. Thanks for help.

Sorry for non technical desciption, but i'm only rookie in CFD software.
Attached Files
File Type: zip example.zip (23.3 KB, 14 views)
slawek.mikula is offline   Reply With Quote

Old   March 30, 2009, 02:47
Default
  #4
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,992
Rep Power: 30
-mAx- will become famous soon enough
I am not at the office today, so I can't check you model, but if you want to apply 2 BC for the same face, you have to have to split your volume along this face, and disconnect this face.
It should create 2 faces at the same location (take care knowing which face belong to which volume for defining your BC).
I will take a look at your dbs file tomorrow
-mAx- is offline   Reply With Quote

Old   March 31, 2009, 03:37
Default
  #5
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,992
Rep Power: 30
-mAx- will become famous soon enough
ok I checked your model.
The 3 volumes you have are the solid part or are they already the fluid domain?
Where should be the flowfield?
-mAx- is offline   Reply With Quote

Old   April 6, 2009, 09:49
Default
  #6
New Member
 
Slawek Mikula
Join Date: Mar 2009
Posts: 5
Rep Power: 8
slawek.mikula is on a distinguished road
I'm really sorry for a late answer, but i haven't received email notification about Your answer (and waited for it).

About the volumes - all of them are solid. The "heat flux" boundary condition will be on the three faces on the top of each volume r_a, r_b, r_c. Everything else should be thermally connected with each other (the heat should spread across all volumes).
slawek.mikula is offline   Reply With Quote

Old   April 6, 2009, 11:45
Default
  #7
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 2,992
Rep Power: 30
-mAx- will become famous soon enough
Is this a pure solid conduction?
no convection through flow?
If yes, then I have no experience
Sorry
But regarding Gambit side, as I said, if you want to apply 2 BC on both sides from a surface, you have to disconnect your volume at this face. Gambit will create a superposed face (on face belong to one volume).
-mAx- is offline   Reply With Quote

Old   April 6, 2009, 12:15
Default
  #8
New Member
 
Slawek Mikula
Join Date: Mar 2009
Posts: 5
Rep Power: 8
slawek.mikula is on a distinguished road
Thanks a lot anyway, i'll try to look for an answer with the superposed face.
slawek.mikula is offline   Reply With Quote

Old   May 2, 2009, 11:23
Default
  #9
New Member
 
Slawek Mikula
Join Date: Mar 2009
Posts: 5
Rep Power: 8
slawek.mikula is on a distinguished road
I've successfully created model I wanted. For future this is how:

- Task: I would like to create on one face ("main face") of an integrated circuit model different areas for the thermal purposes.

- Attempt 1 (fail): I've created many volumes that build that chip and after using "combine" tool on these volumes the faces are combined to one face - FAIL
- Attempt 2 (success): do as above, use "combine" tool to create one volkume. Next create helper face for the "split" tool. Move the face to the position on the main face and use "split" tool on the "main face". Do it as many times to create needed areas on the "main face". Next apply BC definition, meshing etc.
slawek.mikula is offline   Reply With Quote

Reply

Tags
boundary, gambit, temperature, thermal

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
On the damBreak4phaseFine cases paean OpenFOAM Running, Solving & CFD 0 November 14, 2008 22:14
Rotating interpolated boundary condition hani OpenFOAM Running, Solving & CFD 0 July 4, 2006 07:09
UDF for boundary condition setting Luke FLUENT 0 June 1, 2006 04:33
Convective Heat Transfer - Heat Exchanger Mark CFX 6 November 15, 2004 16:55
How to resolve boundary condition problem? sam FLUENT 2 July 20, 2003 02:19


All times are GMT -4. The time now is 20:22.