Hi @Claudio,
the logical sequence of your time loop looks fine. You can also find a quite minimal FSI cpp example in the current develop version of our tutorials in order to compare your setup.
That’s indeed bad, the two norm diff should only be one in your first iteration. Here some ideas and common issues: Does your coupling work with an explicit coupling scheme? Have you tested your solver in a standalone mode without coupling? Do you store/reload your coupling data correctly in the checkpoints (this part is missing in your snippet)? Do you have the interface boundary accidentally constrained in your setup?
Could you provide some additional information on this?
Regards,
David