export mesh data for an explicit selection

Dear all,

I am a relatively new user COMSOL with a lot of Finite Element experience both on the programming and theory level. I started with COMSOL today which went actually quite fine and fast.

I would like to use that to interface assemled system matrices and mesh data to my own solvers. And it was successful for simple shell models.

At this point, I am also wondering if that is possible to export some selected node data or not. What I am directly interested is 'can I create node groups in COMSOL' which can be exported in some kind of text data file format or in binary file format?

Let me be more specific, lets say I have two fixed edges of a square plate and I would like know which nodes are associated with this selected fixed edges so that I can extract the constrained dof infornation myself. These kinds of information might give me more freedom for simple FRF analysis that I would like to conduct.

I learned that I can extract the matrices Kc and K, for instance, for the system stiffness matrix which represent the matrix on which the boundary conditions are applied and the full system matrix without any boundary conditions applied, respectively.

I would like to know or compute the fixed dof information by either getting it from COMSOL(which would be nice since no extra computations will be necessary.) or by iterating over the nodes myself.

Any ideas or pointers are appreciated on this matter.

Best regards,
Umut