Hi Roy, I have started to run some test cases in 2D (subsonic flow over a sine bump) using QUAD9, and have the following observations:
— All FE types tested: LAGRANGE (till 2nd order), SZABAB and BERNSTEIN work fine without AMR, and the solution converges. — 2nd order LAGRANGE FE type, *with h-refinemement* works fine and converges. — Changing FE type to SZABAB and *using h-refinement* leads to unrealistic (huge) residual values immediately after first h-refinement and the plotted solution has odd looking spikes in each element next to a hanging node. This seems to be an expected behavior given the bug described in the libmesh-devel thread you had sent to me. (?) Out of the higher-order polynomials, SZABAB is nested, but BERNSTEIN is not since the whole basis changes as soon as the p-order is modified. Does this bug/discussion affect BERNSTEIN in the same was as it does SZABAB? I mean, if the project_solution, assumes that the change in p-order could be handled with ignoring/zeroing the highest order dof, then that should not be the correct approach for BERNSTEIN polynomials? -Manav On Dec 1, 2013, at 4:30 PM, Roy Stogner <[email protected]> wrote: > > On Sun, 1 Dec 2013, Manav Bhatia wrote: > >> I will working on some hp-adaptation studies in the coming days. >> I will keep you posted about my experience. > > Thanks! > > FYI, the only case where I recall definitely getting exponential > convergence was on 1D problems with a "h refine only for elements next > to predefined singularity points" heuristic. This suggests that we > might have both a bug in the constraints generation and a bug or a > poor design in the coarsening-based hp-selection heuristic. > > IIRC a while ago I identified a possible bug in the constraints > generation but didn't have time to fix it. Let me see... > > http://www.mail-archive.com/[email protected]/msg01928.html > > And yes, that definitely looks like a bug. When we see high-p > edge/face dofs on hanging nodes we're not constraining the right > indices; we need to be testing FEInterface::extra_hanging_dofs and > hitting the nodal dof indices in reverse order in that case. I can > probably cook up a patch for that next week, but I don't have much > time; would you be interested in helping test it? > >> I also owe you another PR on the user sensitivity routines for >> sensitivity analysis. The code is complete at my end and I have >> been using it. I will soon create a PR for the same. > > Thanks! > > Didn't you already have a PR open for that? I could swear I remember > starting to look that over, but going back I can't find it in either > the open or the closed pulls list on github. > --- > Roy ------------------------------------------------------------------------------ Sponsored by Intel(R) XDK Develop, test and display web and hybrid apps with a single code base. Download it for free now! http://pubads.g.doubleclick.net/gampad/clk?id=111408631&iu=/4140/ostg.clktrk _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
