Hamed, 2016-10-31 15:56 GMT-04:00 Hamed Babaei <hamedbabae...@gmail.com>: > I have already checked SSOR and AMG non of them make a difference . ILU > doesn't work and gives this error: "[0]PETSC ERROR: MatSolverPackage petsc > does not support matrix type mpiaij" What do you mean they don't make a difference? You should get a different residual after 10000 steps for each preconditioner.
> I don't know how to increase number of iteration. Although I have used the > "SolverControl solver_control (dof_handler.n_dofs(), > 1e-12*system_rhs.l2_norm());" as solver control and my n_dof is much more > than 10000 but it doesn't go more than 10000 itteration !!! I don't know. This could be a limit in PETSc? I never use PETSc so I don't know. > I was wondering which other preconditioner to use and how to increase number > of iterations . If standard preconditioners don't work very well for your problem, you need a physics-based preconditioner. You will need to find and implement it yourself since it needs to be tailored for your equation. Something that you can also try, it's to restart less often GMRES (http://www.dealii.org/developer/doxygen/deal.II/structPETScWrappers_1_1SolverGMRES_1_1AdditionalData.html) Restarting less often will make GMRES converge faster but you will need more memory. Best, Bruno -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
