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.

What causes a model to converge at one frequency, but not at another?

Please login with a confirmed email address before reporting spam

I have created a coil and am running it at different turn number and frequencies to verify that the model is outputting correct inductance.

Using "magnetic and electric fields" (mef) and a frequency domain study, I am running the following parametric sweeps:

N=5,10,15 turns
f = 10, 50, 100, 500 Hz

However, after running N=5 through all frequencies, N=10 does not converge at f=500 Hz.

Does anyone have any tips on how to tweek the solver?
I am currently running FGMRES and it "slows down" between a convergence of 2-5 while SSOR iterates to 1 000 000 and it gives up.



--
:)

3 Replies Last Post 2016年5月2日 GMT-4 14:57
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 8 years ago 2016年5月1日 GMT-4 14:53
Hi

I believe you do not give us enough info to give back reasonable guesses.

One possibility, taken from the blue, with N=10 and f=500Hz you are hitting a LC resonance without any resistance to damp the signal hence a numerical singularity, but it could be fully other things, like a mesh density issue ...

--
Good luck
Ivar
Hi I believe you do not give us enough info to give back reasonable guesses. One possibility, taken from the blue, with N=10 and f=500Hz you are hitting a LC resonance without any resistance to damp the signal hence a numerical singularity, but it could be fully other things, like a mesh density issue ... -- Good luck Ivar

Please login with a confirmed email address before reporting spam

Posted: 8 years ago 2016年5月1日 GMT-4 15:39

Hi

I believe you do not give us enough info to give back reasonable guesses.

One possibility, taken from the blue, with N=10 and f=500Hz you are hitting a LC resonance without any resistance to damp the signal hence a numerical singularity, but it could be fully other things, like a mesh density issue ...

--
Good luck
Ivar



Greetings, Ivar. It is an honor to have you in my thread :)

My fault is almost bordering idiotic, but I forgot to disable the study "coil geometry analysis" after disabling the multiturn coil.

After that it worked out nicely, and I got good results:

Physical inductor: measured by impedance method at 128 uH
Modelled replikaka in comsol: 126.55 uH

I hope it's not pure dumb luck





--
:)
[QUOTE] Hi I believe you do not give us enough info to give back reasonable guesses. One possibility, taken from the blue, with N=10 and f=500Hz you are hitting a LC resonance without any resistance to damp the signal hence a numerical singularity, but it could be fully other things, like a mesh density issue ... -- Good luck Ivar [/QUOTE] Greetings, Ivar. It is an honor to have you in my thread :) My fault is almost bordering idiotic, but I forgot to disable the study "coil geometry analysis" after disabling the multiturn coil. After that it worked out nicely, and I got good results: Physical inductor: measured by impedance method at 128 uH Modelled replikaka in comsol: 126.55 uH I hope it's not pure dumb luck -- :)


Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 8 years ago 2016年5月2日 GMT-4 14:57
Hi

It's never to late to learn ;)
and we learn more from our "errors" often, than from our successes, so continue like that :)

--
Have fun COMSOLing
Ivar
Hi It's never to late to learn ;) and we learn more from our "errors" often, than from our successes, so continue like that :) -- Have fun COMSOLing Ivar

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.