Menu

Discussion Forum

New Discussion
Filtern

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Warning: New constraint force nodes detected: these are not stored !

Posted 27.11.2009, 07:38 GMT-5 Computational Fluid Dynamics (CFD) Version 4.1 7 Replies

Steven Delrue
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi everyone,

I was trying to model a boundary condition (using assemblies) which varies in time (depending on some parameters). However, when I solve my model, I get the following warning:

New constraint force nodes detected: these are not stored !

Is there anyone who can tell me what this warning means?

Thx,
Steven
7 Replies Last Post 15.03.2011, 05:54 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 2 decades ago 27.11.2009, 10:08 GMT-5
Hi

I got those messages also the other day, I was wrking in assembly mode, with "no imprints" and had defined bounary conditions with bolean limits, using ALE on one side of the geometry, with force analysis on one part.

When I mesh coarse I get the message, by meshing finer they did not appear.

From what I got out, was that some of the ALE nodes were moving in and out of my boundary conditions settings, the solver detected that it should also inlcude/substract new/old nodes for the force clculations, but it was not able to "on the fly" during solving. The force measurements were also somewhat wrong, but the rest seemed to solve OK.

by decreasing mesh size, I did not get any warnings and the results seemd better.

Normally I start with a coarse mesh, and decrease until I have less than 10% changes on the results, while I check the warnings and other

Hope this helps
Ivar
Hi I got those messages also the other day, I was wrking in assembly mode, with "no imprints" and had defined bounary conditions with bolean limits, using ALE on one side of the geometry, with force analysis on one part. When I mesh coarse I get the message, by meshing finer they did not appear. From what I got out, was that some of the ALE nodes were moving in and out of my boundary conditions settings, the solver detected that it should also inlcude/substract new/old nodes for the force clculations, but it was not able to "on the fly" during solving. The force measurements were also somewhat wrong, but the rest seemed to solve OK. by decreasing mesh size, I did not get any warnings and the results seemd better. Normally I start with a coarse mesh, and decrease until I have less than 10% changes on the results, while I check the warnings and other Hope this helps Ivar
Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 2 decades ago 27.11.2009, 10:36 GMT-5
Hi Steven and Ivar. The warning messsage in itself can be considered a bug. It does not affect the reliability of your solution.

For details see
www.comsol.com/support/knowledgebase/1056/

Niklas
Hi Steven and Ivar. The warning messsage in itself can be considered a bug. It does not affect the reliability of your solution. For details see http://www.comsol.com/support/knowledgebase/1056/ Niklas
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 2 decades ago 27.11.2009, 11:03 GMT-5
Hello Niklas

Well I though there were no bugs in COMSOL ;)

In fact you confirm what I suspected, as I was interested in the reaction forces, I will continue to take some cautions when such warnings appear, but as I said above, the results were reasonnable, therefore I was, and I'm still not, alarmed, but ... warned.

have a nice week-end
Ivar
Hello Niklas Well I though there were no bugs in COMSOL ;) In fact you confirm what I suspected, as I was interested in the reaction forces, I will continue to take some cautions when such warnings appear, but as I said above, the results were reasonnable, therefore I was, and I'm still not, alarmed, but ... warned. have a nice week-end Ivar
Nils Eivind Kamfjord
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 08.03.2011, 11:41 GMT-5
If this was a bug in 2009, is it then "re introduced" in 4.1 ?

I keep getting this warning now in a fairly simple turbulent model.
If this was a bug in 2009, is it then "re introduced" in 4.1 ? I keep getting this warning now in a fairly simple turbulent model.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 08.03.2011, 15:25 GMT-5
Hi

It's not a bug, in my view, it's a is says a warning, and warnings are to be analysed to see if they interact with your model results, In some cases it could be dramatic, even if mostly it's harmless.

Fo me so far it is linked to the ALE and the large displacements observed over boundaries with exrternal force/flux conditions

--
Good luck
Ivar
Hi It's not a bug, in my view, it's a is says a warning, and warnings are to be analysed to see if they interact with your model results, In some cases it could be dramatic, even if mostly it's harmless. Fo me so far it is linked to the ALE and the large displacements observed over boundaries with exrternal force/flux conditions -- Good luck Ivar
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 08.03.2011, 22:16 GMT-5
My approach to this problem, but do not actually know for sure is to consider the check box that can be unchecked to evaluate reaction forces. That is what I do to eliminate this warning message. Unless you need to actually know the reactionary forces, it is not needed.

My approach to this problem, but do not actually know for sure is to consider the check box that can be unchecked to evaluate reaction forces. That is what I do to eliminate this warning message. Unless you need to actually know the reactionary forces, it is not needed.
Jérémie GIRARDOT
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 15.03.2011, 05:54 GMT-4
Thanks for this help, I have the same problem, but not with an ALE model. I will try again first with a finer mesh and second by uncheck this box.

I'll keep you in touch

regards

--
--
Jérémie GIRARDOT
Thanks for this help, I have the same problem, but not with an ALE model. I will try again first with a finer mesh and second by uncheck this box. I'll keep you in touch regards -- -- Jérémie GIRARDOT

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content