Re: [Libmesh-users] Reading Mesh produced from Gmsh to use as as Unstructured Mesh--Higher Order Elements?

[Alexander L. <ale...@gm...>]

I've never used pygmsh, but I know if you're running gmsh from the command
line, passing the option `-order 2` will create second order elements.

On Wed, Nov 22, 2017 at 2:14 PM, Roy Stogner <roy...@ic...>
wrote:

>
> On Wed, 22 Nov 2017, Zack Vitoh wrote:
>
>  GmshIO gmsh_io(mesh);
>>  gmsh_io.read("disk.vtu");
>>
>> but--and I am not sure if this is possible--imposing additional nodes on
>> each element generated in the triangularization generated by gmsh with
>> nodes such that I have, say, Tri6 elements.
>>
>
> You have Tri3 elements now?  After the read calling
> mesh.all_second_order();
> will turn them into Tri6 elements.
>
> Is this possible through libmesh, or something I would I have to do
>> something in gmsh instead?
>>
>
> I'm afraid if you have a disk then this is something you *should* do
> in gmsh instead if that's possible.  By the time libMesh reads a
> first-order triangulation, curvature information has been discarded,
> and we don't try to reconstruct it, so you'll still get straight-sided
> elements rather than curved-sided elements.  The only way to get the
> best second-order boundary geometry is to patch it up manually,
> looping over boundary nodes and "snapping" them to the curve where you
> know they should be.
> ---
> Roy
>
>
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