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 The information provided may be out of date.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.

Global Equations defined variable has singular matrix problem?

Please login with a confirmed email address before reporting spam

Dear support,

Does anyone ever meet the following error when using global equations to define a variable as source? I am trying to simulate in 4.3a the enclosed volume of fluid following the COMSOL Blog:
Following the guideline in this blog, I can simulate incompressible fluid by using global equations to define the inner pressure in 2D, but the error comes out when I translated it into a 3D model.

Could anyone please give some hint on possible reason? Thanks.

Failed to find a solution.
Singular matrix.

There are 1 void equations (empty rows in matrix) for the variable comp1.Inner_pressure.
at coordinates: (0,0,0), ...
Returned solution is not converged.

0 Replies Last Post 31-Mar-2014, 6:00 PM GMT-4
COMSOL Moderator

Hello Shuai Ge

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.

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.