CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Fluent UDF and Scheme Programming

UDF for periodic boundary condition

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 31, 2011, 03:35
Default UDF for periodic boundary condition
  #1
New Member
 
Angie
Join Date: Nov 2010
Posts: 17
Rep Power: 7
Angeline is on a distinguished road
Hi Guys

My case is gas solid flow in a pipe. Instead of simulating a long pipe , I take a small length using periodic BC. After every iteration the values from outlet will be updated in inlet. I want to write a UDF for this.

Can anybody help me please.


Regards
Angie
Angeline is offline   Reply With Quote

Old   May 31, 2011, 08:07
Default
  #2
Senior Member
 
Amir's Avatar
 
Amir
Join Date: May 2009
Location: Montreal, QC
Posts: 739
Blog Entries: 1
Rep Power: 14
Amir is on a distinguished road
Hi Angie,
If you don't want to use FLUENT periodic BC (maybe for its restrictions ?), you have to loop over desired faces with an exhaustive search. (it's much more better to have same topologies in two faces)

Regards,

Amir

Last edited by Amir; May 31, 2011 at 12:46.
Amir is offline   Reply With Quote

Old   June 1, 2011, 02:02
Default
  #3
New Member
 
Angie
Join Date: Nov 2010
Posts: 17
Rep Power: 7
Angeline is on a distinguished road
Thanks Amir for your reply.

Can you please elaborate it more for me to understand.......


Regards
Angie
Angeline is offline   Reply With Quote

Old   June 1, 2011, 05:45
Default
  #4
Senior Member
 
Amir's Avatar
 
Amir
Join Date: May 2009
Location: Montreal, QC
Posts: 739
Blog Entries: 1
Rep Power: 14
Amir is on a distinguished road
Quote:
Originally Posted by Angeline View Post
Thanks Amir for your reply.

Can you please elaborate it more for me to understand.......


Regards
Angie
First, ensure whether you can use periodic boundary condition of FLUENT or not; check its restrictions in user manual. If you can use that, it wouldn't need any UDF.
If it doesn't the case, for writing UDF and for simplicity, use the same topology on both faces which you want to project data. After that, you can use 2 procedures:
1) if you have used same topologies and strategies in creating faces, FLUENT searchs faces' elements in the same manner, so you can write data in a temporary files and then use them; in this method, you have to ensure same searching manner.
2) in this method you can use exhausting search between to faces to achive appropriate cells to which you want to project data. (using this method is not reasonable and also time-consuming and it isn't recommended)

Regards,

Amir
Amir is offline   Reply With Quote

Old   April 30, 2012, 08:51
Default
  #5
New Member
 
Learner
Join Date: Nov 2011
Location: Ingolstadt
Posts: 27
Rep Power: 6
raghu.tejaswi is on a distinguished road
Hi Angeline, Amir

I assume the use of periodic BC is to reduce the computational domain. I have been using it to update the values of outlet to inlet in a 2D flow.
I am basically using it to achieve a fully developed flow (Thermally and hydrodynamically).

Amir: Could you pls clarify if I can really use periodic BC to achieve fully developed temperature profile? My results from simulations match with the analytical results but the temperature profile doesnt seem to maintain constant even after 10m length of the pipe. Is there anything I need to note before using periodic BC?

Raghu
raghu.tejaswi is offline   Reply With Quote

Old   April 30, 2012, 10:04
Default
  #6
Senior Member
 
François Grégoire
Join Date: Jan 2010
Location: Laval University, Canada
Posts: 366
Rep Power: 9
macfly is on a distinguished road
Hi Raghu,

Thermally fully developed doesn't mean that temperature profile no longer changes. It is the relative shape of the profile that no longer changes, and the local convection coefficient becomes a constant independent of flow axis.
macfly is offline   Reply With Quote

Old   November 7, 2015, 01:08
Talking Reason for divergence of continuity in Periodic boundary condition
  #7
New Member
 
Luttappy Kuttusan Dakini
Join Date: Oct 2015
Location: India
Posts: 4
Rep Power: 2
Luttappy is on a distinguished road
Hi all
I was working on Periodic Boundary condition for a wavy channel considering one module at a time in Fluent at very low Re (Laminar and steady).
In this case except continuity both momentum and energy equations are converging.
What might be the reason for this issue
Thanks in Advance.
Attached Images
File Type: png Untitled.png (42.7 KB, 10 views)
Luttappy is offline   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
Resolved: Changing boundary condition with UDF according to pressure outlet boundary alpemre Fluent UDF and Scheme Programming 12 February 24, 2014 11:18
Boundary Condition Types Using Scheme and UDF Nasir FLUENT 0 September 15, 2008 21:54
UDF for pressure oulet boundary condition Jubs FLUENT 0 February 13, 2007 01:26
UDF for the boundary condition Sridhar FLUENT 3 July 13, 2001 19:18
UDF : boundary condition ID Flav FLUENT 4 June 28, 2001 09:52


All times are GMT -4. The time now is 21:26.