Hello Barry, Welcome to the party! Thank you guys for your precious suggestions, they are really helpful!
It's been a while since I am messing around and I have tested many combinations. Schur + selfp is the best preconditioner, it converges within 5 iters using gmres for inner solvers but it is not very fast and sometimes multiplicative it's a better option as the inner iterations looks lighter. If I tune the relative tolerance I get a huge speed up, but I am a bit less confident about the results. The funny thing is that the default relative tolerance if commercial CFD solver is huge, very often 0.1 -.- If I may borrow your brain guys for a while, I would like to ask your opinion about the multigrid they use in this paper: https://www.aub.edu.lb/msfea/research/Documents/CFD-P18.pdf. At some point they say: " The algorithm used in this work is a combination of the ILU(0) [28] algorithm with an additive corrective multigrid method [29] ", 29: https://www.tandfonline.com/doi/abs/10.1080/10407788608913491 Is that something similar to fieldsplit additive? Many thanks
