[Dune] Reading arbitrary polygonal meshes in Dune

Thu Feb 26 17:03:44 CET 2015

>
> a simpler, relatively straighforward approach could be
> to read your polygons into gmsh and then have gmsh
> triangulate them, into triangles.

@Benedikt - Yes, that is precisely what I thought I should do but did not
know you could do the triangulation in Gmsh. Any pointers? I still have to
use quadrature on polygons in my code and for that I am going to need the
triangulation anyway.
@Andreas, Christian: I have been having trouble building opm-cornerpoint
module on my laptop. Is it best to seek help on their mailing list to get
it working with Dune?

Thanks
Ganesh

On Thu, Feb 26, 2015 at 2:31 PM, Christian Engwer <
christian.engwer at uni-muenster.de> wrote:

> On Thu, Feb 26, 2015 at 03:05:13PM +0100, Benedikt Oswald wrote:
> > aha. But still, what about triangulating into triangles and assigning a
> > certain tag to a group of elements
> > that form the original polygon, then evaluating the algorthm based on
> > triangles with that same tag ? Benedikt
>
> It will make handling of DOFs nearly impossible. Often you have things
> like one DOF per intersection/face (in the case of conforming polygons
> every intersection corresponfs to a face), but now you have polygon
> internal faces and resolving this is all but simple.
>
> Christian
>
> > Am 26/02/15 um 15:01 schrieb Christian Engwer:
> > > Hi Benedikt,
> > >
> > > he says he wants to use the virtual element method and there the main
> > > idea is to have a method which wokrs on arbitrary polygons.
> > >
> > > Christian
> > >
> > > On Thu, Feb 26, 2015 at 02:56:01PM +0100, Benedikt Oswald wrote:
> > >> 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
> > >>>>>
> > >>>>>
> > >>>>> _______________________________________________
> > >>>>> Dune mailing list
> > >>>>> Dune at dune-project.org
> > >>>>> http://lists.dune-project.org/mailman/listinfo/dune
> > >>>> _______________________________________________
> > >>>> Dune mailing list
> > >>>> Dune at dune-project.org
> > >>>> http://lists.dune-project.org/mailman/listinfo/dune
> > >> --
> > >>
> ------------------------------------------------------------------------------------------------
> > >> Dr. sc. techn. Benedikt Oswald - first engineer - LSPR AG - phone - +41
> 43 366 90 74
> > >> Technoparkstrasse 1, CH-8005 Zürich, benedikt.oswald at lspr.ch - labor
> vincit omnia improbus
> > >>
> ------------------------------------------------------------------------------------------------
> > >>
> > >>
> > >> _______________________________________________
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> > >> Dune at dune-project.org
> > >> http://lists.dune-project.org/mailman/listinfo/dune
> > >>
> >
> > --
> >
> ------------------------------------------------------------------------------------------------
> > Dr. sc. techn. Benedikt Oswald - first engineer - LSPR AG - phone - +41
> 43 366 90 74
> > Technoparkstrasse 1, CH-8005 Zürich, benedikt.oswald at lspr.ch - labor
> vincit omnia improbus
> >
> ------------------------------------------------------------------------------------------------
> >
> >
>
> --
> Prof. Dr. Christian Engwer
> Institut für Numerische und Angewandte Mathematik
> Fachbereich Mathematik und Informatik der Universität Münster
> Einsteinstrasse 62
> 48149 Münster
>
> E-Mail  christian.engwer at uni-muenster.de
> Telefon +49 251 83-35067
> FAX             +49 251 83-32729
>
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