On Wed, 4 Dec 2013, Manav Bhatia wrote:
— 2nd order LAGRANGE FE type, *with h-refinemement* works fine and converges.
This is as I'd expect - the current libMesh adaptive p-refinement code
assumes a hierarchic basis and should fail in weird ways (or in devel
mode, throw an error) without one.
— 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. (?)
No, actually. The bug I described should affect adaptive
hp-refinement, but not pure adaptive h-refinement.
What p level and element type were you using that you saw a failure
with h-refinement? I don't know much about the SZABAB elements but
it looks like perhaps they require extra_hanging_dofs==true but aren't
getting that in fe_interface.C.
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?
With non-nested (what I called "hierarchic" before, not referring only
to the HIERARCHICs) polynomials we don't support p-refinement at all
yet. That's not so much a bug as an unimplemented feature.
---
Roy
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