[petsc-dev] higher-order coordiate fields in DMPlex

[Matthew Knepley]

On Fri, Jun 2, 2017 at 7:55 PM, Jed Brown <jed at jedbrown.org> wrote:

> Matthew Knepley <knepley at gmail.com> writes:
>
> > On Fri, Jun 2, 2017 at 5:04 PM, Alberto Paganini <
> > Alberto.Paganini at maths.ox.ac.uk> wrote:
> >
> >> Dear PETSc developers,
> >>
> >> I'm Alberto and I'm a user of the finite element library Firedrake,
> >> which relies on DMPlex to import meshes.
> >>
> >
> > Great.
> >
> >
> >> In order to use higher-order FEs, it is desirable to import higher-order
> >> meshes.
> >>
> >
> > I really do not like that term. Let me try and convince you that it is
> > wrong. The topology of the
> > mesh is unchanged. You are only talking about the order of the
> > representation of the geometry
> > field. Thus, it is not the mesh that is "higher order", but the geometry.
> >
> >
> >> I've been told that DMPlex does not offer this future (at present).
> >>
> >
> > Toby just merged this to master, so I think we can say that we have alpha
> > support for this. How
> > does it work? We already have a coordinateDM and coordinates Vec, so you
> > just choose a
> > higher order discretization for the DS inside the coordinateDM. Does that
> > make sense?
>
> Can it load quadratic geometry from a file (ExodusII or otherwise)?
>

If someone requests a given file format, we can do it. That's how we always
proceed.

   Matt

That's the interesting part -- the quadratic geometry is rarely
> interesting except in elements that touch the boundary and you can't
> infer the true curved boundary without access to a geometric model (a
> much more cumbersome software stack).
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

http://www.caam.rice.edu/~mk51/
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