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

convergence criteria by lift and drag coefficent

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 17, 2011, 06:37
Default convergence criteria by lift and drag coefficent
  #1
New Member
 
Join Date: Feb 2011
Posts: 2
Rep Power: 0
xtof is on a distinguished road
Hello,

I have modelled a flow over an airfoil in cfx which works fine so far. Futhermore i have created monitorpoints for lift- and drag-coefficent.
What i want to do now is to set a interrupt control condition in cfx pre so that the actual value of the coefficent is compared to the one ten iterations before. If the difference is under a defined limit (let's say 0.1%) the simulation should be stoped.
My problem is that I don't know the CEL-Syntax to get a value at a certain iteration.

Maybe somebody knows how to program that.

Thanks
xtof is offline   Reply With Quote

Old   March 18, 2011, 07:44
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,854
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
This cannot be done easily in CEL.

You will probably find a residual convergence tolerance to correspond to your coefficient convergence. Then you could just use a simple residual convergence tolerance.

If you insist on using your coefficients to judge convergence then I would have a cron job running in the background (ie outside of CFX) which monitors the monitor point output files and when it senses convergence it runs the cfx5stop command.
ghorrocks is offline   Reply With Quote

Old   March 18, 2011, 07:50
Default
  #3
New Member
 
Join Date: Feb 2011
Posts: 2
Rep Power: 0
xtof is on a distinguished road
Thanks for the reply. I think I'll go with the normal residuals so far. I had a phoncall with the CFX-Support yesterday and they told me the same. Maybe when I have more time I'll try to pragramm some tool to monitor the coeffiecents and stop the solver run.
xtof is offline   Reply With Quote

Old   March 18, 2011, 15:38
Default
  #4
Senior Member
 
Join Date: Mar 2009
Location: Europe
Posts: 169
Rep Power: 17
joey2007 is on a distinguished road
The service send me an user fortran example, which stores older values, some time ago. I am not permitted to distribute further, however you may get it if you ask.
__________________
-
-
-
-
-
------------------------------------------------------------------------
Please do not forget: I am not paid for answering your questions.


Thousands of issues can cause a division by zero. Please do not capture a thread, with the argument: "I have the same issue ...."
joey2007 is offline   Reply With Quote

Reply

Tags
cel expression, coefficient, convergence, drag, lift


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lift and Drag ??? Yogibear STAR-CCM+ 5 November 2, 2023 18:14
Lift and Drag Monitor Point Values Converging to Zero Josh CFX 24 May 9, 2011 11:38
Correct lift but wrong pressure drag - possible? zx Main CFD Forum 4 July 28, 2007 00:38
drag and lift coefficient Noé Siemens 5 July 13, 2004 11:21
Fluid mechanics / drag & lift Jamcam Main CFD Forum 0 October 31, 2002 05:39


All times are GMT -4. The time now is 11:45.