Hello everyone, I am currently solving a GLS stabilized form of the Navier-Stokes equation using DEALII. The residual of the system looks similar to the regular Incompressible Navier-Stokes, except that a stiffness matrix that is dependent on the element size is added to the P-P block. I have a great success / scaling when solving Manufactured Solutions and I have been able to reach relatively decent P1-P! meshes (say 2056x2056 or 256x256x256) on a workstation computer. I am currently using the GMRES Trilinos Wrapper with ILU preconditioning with a relatively high fill-in level (4).
One of the issue of my system is that the pressure is defined up to a constant. On coarse mesh this does not affect the GMRES solver. However, on finer mesh, it seems that the GMRES Solver is greatly affected by this near-singularity of the matrix system. I have often read in the literature that for stabilized method, the best way was to remove the "mode" associated to a constant pressure. I believe this implies some sort of projection of the residual in a space without a pressure constant? I know this is a very broad question, but how would I go and implement such a thing in my solver? Are there any examples in DEALII where a Poisson problem is solved but with strictly Neumann boundaries? That would be a very similar problem that could guide me in the right direction. Thank you very much for your help. The support of this forum is greatly appreciated. -- 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.
