Wolfgang, Thanks for your reply, and also for being cautious on which which tree to bark up :-)
* For the case of adaptive refinement, the solution looks discontinuous also at edges without refinement. Is that reasonable? What's the element you are using? I am currently using 2nd order FE_DGQ elements. Unfortunately, no, the solution certainly should not be discontinuous at any point in the domain. My sense is that something is incorrect in my program's assemble_system function, which in turn causes the computed solution to be wrong. The picture from the adaptive refinement case was simply intended to support this point. To reiterate, what is incorrect is not an issue in the case of uniform refinement-- if I take the mesh with 4x4 cells and refine to 8x8, the energy norm error decreases accordingly. This continues with repeated refinements; I see reasonable convergence rates as I drive $h$ to zero. Short of posting my assemble_system code, does this behavior sound like anything you have seen before? Would be grateful for any other places to look. * One of the things worth keeping in mind is that what you are visualizing is a piecewise linear representation of the solution. However, I suspect you are using a higher polynomial finite element. In other words, what you see in Visit is not what the solution *actually* is. Take a look at the documentation of DataOut::build_patches() for a discussion of how this can be addressed by using subdivisions of the mesh to get a closer representation of what you are computing. This is good to keep in mind, thanks for pointing out. At the current moment, however, I think the situation is a bit more complicated, for the reasons mentioned above and in my first message. Best regards, -Sean -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/66f6a80d-03a4-470e-9e31-d47a49e73a8bn%40googlegroups.com.
