Menu

Discussion Forum

New Discussion
Filtrer

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 The information provided may be out of date.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.

Problem with differentiation operator ( zero result )

Posted 16 févr. 2012, 04:49 UTC−5 MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Parameters, Variables, & Functions, Results & Visualization Version 4.2 2 Replies

Mousavi Hasan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello to all

I set up a "tem" physics interface ( joulheating and thermal expansion) and want to get a spatial derivative from some variable such as stress , pressure and temperature. I used Tx , ux , d(u,x) , d(tem.p,x) , etc. but it gives zero everywhere in the domains as result.

I've read the forum and changed the shape function to cubic but the results doesn't change.

Also, I have added a PDE in the form of u2 = d(T,x) but the given results is obviously meaning less and wrong and doesn't match with the temperature gradient which is a predefined result for "tem" !

I don't know what else I can do.
2 Replies Last Post 18 févr. 2012, 06:57 UTC−5
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 17 févr. 2012, 15:06 UTC−5
Hi

if you are in V4.2a, I believe it's TX the derivative w.r.t. the material frame, (and not Tx the derivative of the spatial frame)
the same for uX and uXX, and for d(d(tem.p,X),Y), use upper case X,Y,Z,R

At least that works for me in V4.2a, even nicer & smoother with cubic or quartic shape functions

--
Good luck
Ivar
Hi if you are in V4.2a, I believe it's TX the derivative w.r.t. the material frame, (and not Tx the derivative of the spatial frame) the same for uX and uXX, and for d(d(tem.p,X),Y), use upper case X,Y,Z,R At least that works for me in V4.2a, even nicer & smoother with cubic or quartic shape functions -- Good luck Ivar
Mousavi Hasan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 18 févr. 2012, 06:57 UTC−5
Dear Ivar
Thank you very much, it worked. God bless you :)

Kind regards
Dear Ivar Thank you very much, it worked. God bless you :) Kind regards

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