Hi Wolfgang, I believe the formula is correct. the cubic term comes from p=z^3 being the pressure manufactured solution. so in (pI-2e) you get a z^3 term and indeed a linear term in the 2e portion.
The code commpiles and the error analysis is correct with Dirichlet conditions on the top and bottom (sides are no flux still). With the code snippet where Neumann conditions are used at the top and bottom, the code compiles and runs, and strangely, with the error analysis being correct for the pressure, but not for the velocity. The velocity profile qualitatively looks ok, but is quite off the exact solution and the error doesn't converge with the refinement level. This is how I have come to conclude that it is how i am implementing the Neumann conditions that are causing the problem, since with Dirichlet conditions the solver is good. All i can figure out is that perhaps we have calculated the vector g_N (Neumann condition) incorrectly, but that has been checked multiple times - if anyone notices something stupid we have done here then do let us know too. I will for now use vector extractors like you suggested and see if that helps at all? Many thanks -- 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.
