Elmer Discussion Forum

Hi everyone,

I was playing a little with the Whitney AV Solver in the last days and I am really impressed. However I noticed that convergence for a practical model size (> 10^6 elements) is hardly reachable without preconditioning (as expected for a curl curl matrix). Unfortunately, even with ILU I am not able to converge to a solution. Using the same model with a coarser mesh on the other hand works fine. So currently I am trying the TFQMR Solver without preconditioning. Has anybody a better suggestion or has experience with Elmers Whitney AV Solver and larger models and convergence issues?

carsten

Hi,
If you haven't done so already, you could try using BiCGStabL instead of TFQMR, also
adding "BiCGStabL Polynomial Degree=4" might help(?) GMRES with the
"Linear System Gmres Restart=n" is also an option.

Using ILU might actually make things worse.
Regards, Juha

Hi Juha,

BiCGSTABl seems to do the trick. The simulation is still running but slowly converges. I post an update when it is done.

Thank you!

carsten

Hi Juha,

the simulation did converge so BiCGStabL works. Just one more questions: Might the convergence rate be further improved by a higher polynomial degree?

carsten