Hi,
> On Nov 6, 2019, at 12:27 PM, Stogner, Roy H <[email protected]> wrote:
>
>
> On Wed, 6 Nov 2019, gmail wrote:
>
>> I noticed that periodic BC does not work for FEClough. I see the
>> functions for it but I’m guessing it was never implemented.
>
> Could you be more specific?
> FEGenericBase::compute_periodic_constraints is supposed to work for
> every scalar-valued FE type.
I’m doing a nonlinear mixed laplacian and bilaplacian with PetscDM.
My energy is something like:
E=\int \left(w(\phi)+A(\nabla\phi/|\nabla\phi)^2 \xi^2 |\nabla\phi|^2
+\beta\xi^4 |\nabla^2\phi|^2 \right) dx (1)
where w is a polynomial and A is a messy scalar function of vector the normal
to \phi (\nabla\phi/|\nabla\phi).
I’m trying to solve the nonlinear Euler-Lagrange
\partial E/\partial \phi (\tilde{\phi})=0 \forall\tilde{\phi}
(2)
The natural boundary condition of this gives some messy flux on the boundary =
0.
No when I try to solve (2) with \phi interpolated with FEClough, if I enforce
periodicity it does not work and gives me exactly the same solution as though
the periodic boundary is not there.
When I do the same with \beta\equiv0 and solve (2) with FELagrange and periodic
it works perfectly as expected.
>
>> My question is wether periodic BCs do work for FEHermite or is there
>> a reason why the current implementation would not work for C1
>> basses.
>
> We combine Hermite bases with periodic BCs in miscellaneous ex7,
> though I don't think we have good enough assertion coverage of the
> results for me to swear there's been no regressions, especially if
> you're correct and something's no longer working with the
> Clough-Tocher basis.
Thanks. I guess to reproduce the error, I can try to replace Hermite with
Clough-Tocher and see if this gives the same output!
> ---
> Roy
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