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 The information provided may be out of date.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 Large domain

Hi

I am simulating propagation through a simple waveguide in 3D.
The simulation is working perfectly as long as the length of the waveguide is below 10um. When I increase the device length to 10um, the simulation continues and reaches the convergence, however at the final step an error message appears. as below.

Failed to find a solution.
Very ill-conditioned preconditioner.
The relative residual is more than 1000 times larger than the relative tolerance.
Returned solution is not converged.

I have attached the file. I would appreciate any suggestions.

Thank you

Kapil


2 Replies Last Post Feb 12, 2015, 9:40 AM EST
COMSOL Moderator

Hello Kapil Debnath

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Mohammed Thameemul Ansari
Posted: 3 years ago Feb 8, 2015, 9:40 PM EST
Hello sir

The same error am facing now. Did you fix the problem?

May i know what is the solution for the problem?

The relative residual is more than 1000 times larger than the relative tolerance.
Returned solution is not converged.
Hello sir The same error am facing now. Did you fix the problem? May i know what is the solution for the problem? The relative residual is more than 1000 times larger than the relative tolerance. Returned solution is not converged.

Walter Frei COMSOL Employee
Posted: 3 years ago Feb 12, 2015, 9:40 AM EST
Dear Kapil,

You may want to check the geometric scales here. You would want units of microns, not meters.
Dear Kapil, You may want to check the geometric scales here. You would want units of microns, not meters.

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.