[Dune] Reading arbitrary polygonal meshes in Dune

[Benedikt Oswald]

Hello Ganesh

a simpler, relatively straighforward approach could be
to read your polygons into gmsh and then have gmsh
triangulate them, into triangles. The same approach
would also work in 3D. Then, there is not need to
write a new grid. Greetings, Benedikt

Am 26/02/15 um 14:49 schrieb Christian Engwer:
> Hi,
>
> currently no grid can handle such elements. Once upon a time there was
> a simple implementation, which was able to handle arbitrary polygonal
> elements in 2D with out refinement. But this doesn't work with the
> current Dune anymore. On the other hand I believe it wouldn't be too
> difficult to implement such a mesh, as we have introducent several
> changes in the interface to allow for non-standard meshes (this was
> all with the cornerpoint mesh in mind).
>
> Ciao
> Christian
>
> On Thu, Feb 26, 2015 at 12:02:02PM +0000, Andreas Dedner wrote:
>> Hi.
>> The main problem is not the grid type or the factory but that you
>> need an actual
>> grid implementation that can handle these general meshes. ALU and
>> SPGrid etc.
>> can only handle cubes and simplex elements and that is the only
>> geometry types
>> they can understand in their GridFactory.
>>
>> So for something more general you need to provide a new grid
>> implementation that
>> allows for more general grid types. The geometry type of these
>> elements would be
>> "none" and probably you would also be implementing only part of the
>> geometry interface.
>> Something along those lines was done in the CornerPointGrid implementation.
>> https://github.com/OPM/dune-cornerpoint
>>
>> Best
>> Andreas
>>
>>
>>
>> On 26/02/15 11:38, Ganesh Diwan wrote:
>>> Dear list,
>>>
>>> I am working on implementing virtual element computations inside
>>> Dune. This will involve implementing the algorithm on arbitrary
>>> shaped elements. Is there a way to read arbitrary polygonal (2d)
>>> or polyhedral (3d) meshes in Dune? Currently implemented Grid
>>> managers (ALUGrid, SPGrid etc.) identify either simplices or cube
>>> types.
>>>
>>> Can the GridFactory class be used for this purpose? Grid-howto
>>> document says when building a new gridtype Dune may have a problem
>>> for unidentified element type. Say, I have an element with five
>>> edges (a pentagon). In this case, is Dune likely to throw an
>>> exception for unidentified element type?
>>>
>>> I wanted to get the Grid guru's thoughts before investing time in this.
>>>
>>> Thank you!
>>> Ganesh
>>>
>>>
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>

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