Hello Rahul Seth ,

Please can you provide some more details - what exactly are you trying to solve?

I have seen this occur for a range of reasons.

My first recommendation, as always, would be to first go back through the model and ensure that all the boundary conditions are appropriately defined, along with initial values of the system.

You can use the equation viewer to analyse exactly what COMSOL is solving - go through the mathematics and check that it appropriately defines your system.

Check the mesh - it may be too coarse or too fine. You may need to provide different mesh sizes for different regions of the model.

Next, you may wish to change some of the default values for material properties (e.g. conductivities) to non-zero values (often the default values can be zero).

Finally, if you still have problems you should contact COMSOL, I have found they offer fantastic customer service for their customers.

Jules

Most probably the boundary conditions are not properly defined. Have you supplied the required voltages and ground conditions to the relevant parts of your geometry?

Dear Rahul,

COMSOL is telling you that the stiffness matrix is not well defined (empty for the dof V). Very likely you either forgot to add a domain into your physics or you have not defined the boundary conditions properly.

Kind regards,

Julian

Thank You Jules Lloyd Hammond , Abhik Jash and J. Anaya for your replies. I did change the parameters mentioned by you. It did solve my current problem in hand.