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

[Jed Brown]

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)?
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).
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