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

couples or not couples...

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 26, 2003, 10:26
Default couples or not couples...
  #1
giosue
Guest
 
Posts: n/a
Hi.... I need a suggestion... My computational domain has an intersection between a round pipe and a box, they are mutually orthogonal... Whether I use the arbitrary couples at interface between the two solid, can I've problem in solution? Do you think is better, for the solution, to mesh the entire domain without couples? Thanks a lot...
  Reply With Quote

Old   February 26, 2003, 11:09
Default Re: couples or not couples...
  #2
Murali
Guest
 
Posts: n/a
<font face = "Courier New">I am not sure if I understand your question right. If you are skeptical of creating couples, the best way will be to create a conformal mesh. And for interfaces like the ones you have mentioned, the best thing to do is to create a shell surface and extrude. In all my mesh creations, what I have ever used is the following stmt.

cpmatch all

It forms all new couples by itself. Do not try to match couples manually. STAR-CD does this coupling effectively automatically.

After you have created the couples do a geometry check. It should report no cracks. That would mean your mesh is good.

Murali

</font>
  Reply With Quote

Old   February 26, 2003, 11:48
Default Re: couples or not couples...
  #3
cjtune
Guest
 
Posts: n/a
Make sure you use *partial* arbitrary coupling (create a new couple type or just modify the existing couple type 2).

I think also conservation is not as strongly enforced at the interfaces where there are couples as they are essentially interpolations of the fluxes. Also, phenomena like separation of flow at the joint may not be well represented. But then again, the loss in accuracy could be very minor compared to that from your mesh quality.

  Reply With Quote

Old   February 26, 2003, 12:03
Default Re: couples or not couples...
  #4
Jens
Guest
 
Posts: n/a
Hi

A good way to form new couples are:

cpdel all cpma all save

This will delete any old couples and form new ones.

Hope this helps ..

Regards

Jens
  Reply With Quote

Old   February 28, 2003, 06:46
Default Re: couples or not couples...
  #5
steve
Guest
 
Posts: n/a
I don't think what you said is accurate. At couples, faces are split into subfaces and the fluxes are apportioned accordingly. They are not interpolated. There really should be no loss of accuracy.
  Reply With Quote

Old   March 1, 2003, 01:11
Default Re: couples or not couples...
  #6
cjtune
Guest
 
Posts: n/a
Oops. Typing hand quicker than brain...

Like steve says, fluxes are apporportioned appropriately for each face in a couple and conservation is enforced In fact, the couples split the mating faces into subfaces and the member cells then in effect become... polyhedral cells.

I made my original conclusion from this: "...care is taken, via appropriate interpolations in time and space, to preserve flux continuity across the interface and avoid introducing spurious perturbations to the flow field." Pg.13-5 of the methodology manual. Section on sliding boundaries.
  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
Cell Couples in CCM+ norbinou CD-adapco 4 September 10, 2007 10:00
about couples bv CD-adapco 1 July 24, 2005 07:05
couples issue carno CD-adapco 1 April 16, 2004 02:58
Boundary Couples ale CD-adapco 0 January 26, 2004 06:09
couples in ver 3.100B Bo Jensen CD-adapco 1 July 10, 2001 06:37


All times are GMT -4. The time now is 01:57.