If your problem is time dependent, try to start with very small, non-zero, initial time. Also, the time step should be reduced when your mesh goes more refined.

Dear Lucas,

unfortunately I do not have the CFD module available right now, is this the problem you are trying to solve?

https://www.comsol.com/model/vibrating-beam-in-fluid-flow-9408

If that is the case you need to be very careful on how you modify the simulation domain and boundary conditions. The structure is very close to the inlet and the convergence will be heavily affected by the flow velocity. Also the length of the domain is carefully chosen in that example for the conditions they are solving... if you are trying to scale the flow velocity I think you will need to scale the domain and re-mesh accordingly.

Kind regards,

Julian

Hi Lucas,

the error you get is:

"Nonlinear solver did not converge.

Maximum number of Newton iterations reached.

Time : 0.3154687499999999

Last time step is not converged."

This can be wrong physics, coarse mesh, non-linear loads, not correct material properties (such as to small Young modulus) etc. Try to use ramping functions for the loads and the boundary conditions, otherwise your initial conditions will be in conflict with your boundary conditions. It can also be just a numeric problem, which you could simply solve by increasing the maximum number of allowed iterations. In order to find the solution to your problem you should make a plan a try everything, this is the only way to learn about the behaviour of your problem and to study it properly!

Best regards,

Antoni

Thank you for the answers!!

I tried some changes and right now it’s on 16000 iterations and no errors yet. Not much hope for convergence though 🤔