About steady analysis

my question is:
1 for steady analysis, existence of explicit scheme?
2 if no explicit scheme, how can I use acceleration when steady ?

I am not sure if implicit coupling (i.e., IQN/Aitken) makes much sense for a steady-state simulation. I would use an explicit scheme for that, but depends a bit on what you want to couple.

See also Coupling scheme for steady-state FSI - #5