CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

Asymptotic stopping criterion is not working

Register Blogs Community New Posts Updated Threads Search

Like Tree1Likes
  • 1 Post By rob50904

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 25, 2013, 08:05
Default Asymptotic stopping criterion is not working
  #1
New Member
 
rob roy
Join Date: Jun 2011
Posts: 3
Rep Power: 15
rob50904 is on a distinguished road
Hello,
I have a problem with the user defined asymptotic stopping criterion in StarCCM+ 7.06:

I'm calculating the resistance of a ship using free surface with VOF and DFBI (6DOF).

I created a stopping criterion from a force monitor. The plot of the force monitor is decreasingly oscillating. Using the asymptotic stopping criterion for the outer iterations I want to stop the calculations ones the oscillation is within a certain limit for a certain time.
In the stopping criterion I set number of samples to 10 and |Max-Min| to the desired oscillation limit.
My problem is that the criterion is never fulfilled, no matter how high I set the oscillation limit.

example: over a period of 10 timesteps my plotted force changes about 1N. So I would expect a criterion with 10samples and |Max-Min|=2N to immediately stop the calculation but that doesn't happen (the "criterion satisfied" checkbox is "false" all the time).

The Minimum and Maximum criteria work fine by the way!

Did anybody encounter the same problems? Might there be a bug in StarCCM+?
Arsham likes this.
rob50904 is offline   Reply With Quote

Old   January 27, 2013, 11:13
Default
  #2
Member
 
Ryan Coe
Join Date: Jun 2010
Location: Albuquerque, NM
Posts: 98
Rep Power: 16
ryancoe is on a distinguished road
I encountered this same issue a while ago. Like you I was confounded.

When I finally talked to a CD-adapco rep., he explained that the asymptotic limit is simply controlling the inner iterations (this makes sense when you look at the node structure in the GUI). When the limit is met, the simulation advances to the next time-step.

I agree that it would be nice to have an asymptotic limit to end the unsteady simulation. You could try to write a field function or macro like:

if: (asymptotic condition met)
then: set TimeLimit = (CurrentTimeLevel - 1s)
__________________
Ryan
ryancoe is offline   Reply With Quote

Old   January 28, 2013, 09:25
Default
  #3
New Member
 
rob roy
Join Date: Jun 2011
Posts: 3
Rep Power: 15
rob50904 is on a distinguished road
Thanks!
I will try that.
rob50904 is offline   Reply With Quote

Reply


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
problem with Min/max rho tH3f0rC3 OpenFOAM 8 July 31, 2019 10:48
DPM parallel is not working but serial is working johnwinter FLUENT 1 March 27, 2012 03:01
Working Principle of Micro-Oven aero Siemens 2 January 31, 2007 06:00
Help required on working of Micro-oven aero CFX 4 January 19, 2007 09:21
convergence criterion Dominique FLUENT 5 November 24, 2006 03:36


All times are GMT -4. The time now is 16:07.