Matthew Knepley <[email protected]> writes: > On Fri, Jun 2, 2017 at 7:55 PM, Jed Brown <[email protected]> wrote: > >> Matthew Knepley <[email protected]> writes: >> >> > On Fri, Jun 2, 2017 at 5:04 PM, Alberto Paganini < >> > [email protected]> 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.
Okay. When people ask about higher order geometry for unstructured finite elements, I think that about 90% of the time they're really asking whether it can read quadratic geometry from a file. I hate that ExodusII is a cumbersome dependency, but it might be the most useful to add. This wouldn't be just cosmetically checking a box because this can make a big accuracy difference -- quadratic elements have a really hard time paying off for engineering problems if you don't also have quadratic geometry.
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