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

Advanced constraint

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 20, 2002, 10:12
Default Advanced constraint
  #1
CFX 4.3 user
Guest
 
Posts: n/a
Hey people,

I am building a relatively simple setup using CFX 4.3. A room with rectangular inlet and outlet, with five small heat generating rectangular prisms sit on the floor of the room. The application of constraint really annoys me. I have applied advanced constraints on the floor of the room and base of all the five heat generators, I can mesh it but while I run volmsh, it comes that inconsistentelements formed. I could not find any clue on the manual, Is there any one who knows the problem?

Thank you in advance for your reply

CFX4.3 user

  Reply With Quote

Old   February 20, 2002, 11:14
Default Re: Advanced constraint
  #2
CFXboy
Guest
 
Posts: n/a
The problem you are facing is that some of the nodes and the mesh seeds are not located at the same position, resulting in triangular meshes and inconsistent elements. Inconsistent elements mean that the number of elements on opposite faces are not equal. To solve the problem, I would recommend you using the simple constraints, which is much easier.

If you have no choice but to use advance constraint, make sure the nodes and mesh seeds are located on the same spots. This can be done by associate/curve/curve command. I believe you might have done this. Sometimes, this might still result in inconsistent mesh. The next step would be to create the subordinate surface (surfaces that cover the floor) so that the endpoints of the subordinate surface are located at the mesh seed. For example, if you would like the floor to have mesh seeds of 6 by 6 and a 2 by 2 inlet patch in the middle, first create 9 surfaces of 2 by 2. You can create another 2 points on the floor edges using the create/point/interpolate command. Make sure the manifold command is on if your floor is not flat. With this command you can create several more points on the other floor edges. Next create the curves between the points that you have just created (manifold if surface is not flat) and create the surbordinate surfaces by create/surface/manifold command. Finally, associate the curves after you create all the subordinate surfaces.

I hope this helps.

CFXboy
  Reply With Quote

Old   February 20, 2002, 11:27
Default Re: Advanced constraint
  #3
CFX 4.3 user
Guest
 
Posts: n/a
CFX Boy

As the manual recomends I create subordinate surfaces the completely covers the whole floor by Geometry/create/surface/vertex command,. Then I associate the overlaping curves of the big room and the smaller subordinate using Associate curve curve. Then I meshed the whole geometry using 0.1 element length. That was how did it, this thing really making me crazy for about a month, I will try it again using your suggestions.

Thanks for your advise

CFX 4.3 user

  Reply With Quote

Old   February 20, 2002, 12:46
Default Re: Advanced constraint
  #4
cfd guy
Guest
 
Posts: n/a
Hi,
Instead of wasting a lot of your time trying to know how the advanced constraint works, why don't you break your single block into N blocks so that you have a specific surface (patch) for every of your five heat generators giving you no meshing problems? I only have used single constraint and with great care, but advanced constraints I gave up how it works a long time ago.
Good luck! cfd guy
  Reply With Quote

Old   February 21, 2002, 04:41
Default Re: Advanced constraint
  #5
CFX 4.3 user
Guest
 
Posts: n/a
Hi cfd guy,

Thank you very much for your reply. I do not understand you when you say 'break the block' I have five solids sited on the floor. All the five are different solids, I am creating a constraint between the lower face of each heat generating blocks and the floor of the room, that was the idea which wanted to be implemented.

Have a blessed day

CFX user

  Reply With Quote

Old   February 21, 2002, 10:05
Default Re: Advanced constraint
  #6
cfd guy
Guest
 
Posts: n/a
Hello again,
I guess I know what is your problem. Actually you have 6 solids, 5 heat generators and 1 big room. The main thing is that you cannot generate your mesh just creating several blocks inside and one bigger outside. You must satisfy some conditions and this conditions are the Multi-Block structure used by CFX-4. If you are begginer in the code, I'd suggest you to take a look at CFX-4 manual or even visit the CFX Comunnity Pages and download some online courses that might help you in your journey.


Regards, cfd guy.
  Reply With Quote

Old   February 22, 2002, 09:50
Default Re: Advanced constraint
  #7
cfx 4.3 user
Guest
 
Posts: n/a
Hi cfx Guy

You propose to break the heat generating blocks into N blocks in order to avoid implementing advanced constraints, and having no problem during meshing. Can you explain me how to do it? I really do not know this method.

Thank you for your help

Best regards

cfx 4.3 user
  Reply With Quote

Old   February 22, 2002, 11:16
Default Re: Advanced constraint
  #8
cfd guy
Guest
 
Posts: n/a
Hi... Write me an e-mail and I'll send you an simple example.
Regards, cfd guy
  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
mykEpsilon - How to set a min/max constraint for a term with units elektra79 OpenFOAM 3 October 12, 2010 18:12
How can I learn advanced parts of OpenFOAM? mmahdinia OpenFOAM 2 August 27, 2009 08:35
advanced output huwei CFX 1 March 21, 2001 15:43
Advanced Constraint Monir Hossain CFX 2 January 23, 2001 11:42
Advanced Constraints Sudarshan Kumar CFX 2 November 7, 2000 13:56


All times are GMT -4. The time now is 22:32.