dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Jun 22, 2009 at 12:46:09PM -0600, Bartosz Sawicki wrote:
> Kent Andre wrote:
> > On ma., 2009-06-22 at 00:40 -0600, Bartosz Sawicki wrote:
> >> On 22/06/09 12:06 AM, Anders Logg wrote:
> >>> On Sun, Jun 21, 2009 at 11:36:29PM -0600, Bartosz Sawicki wrote:
> >>>> On 19/06/09 02:53 PM, kent-and@xxxxxxxxx wrote:
> >>>>> When using VMTK the boundary indicators are stored as a set of arrays
> >>>>> with names
> >>>>> boundary facet cells,
> >>>>> boundary facet numbers
> >>>>> boundary indicators
> >>>>> The two first arrays are used to find the global facet numbers.
> >>>>> The function computes a mesh function based on these arrays.
> >>>>>
> >>>>> This was what Anders prefered since VMTK does not now anything
> >>>>> about the global numbering of facets in Dolfin (without linking it into
> >>>>> Dolfin).
> >>>>>
> >>>>> This is not a VMTK specific problem, but I do think VMTK is the only
> >>>>> mesh-generator
> >>>>> that let you store boundary indicators at the moment. I guess we should add
> >>>>> this to NetGen as well, both Hans Petter Langtangen and Douglas Arnold has
> >>>>> bugged
> >>>>> me about this the last few days.
> >>>> I'm every day user of this functionality. I use Netgen generated models, 
> >>>> but also other software which add boundary indicators to existing 
> >>>> meshes. Netgen supports boundary indicators quite well, both by geo 
> >>>> files, and by GUI. I don't understand what you want to add?
> >>> Is it possible to set DOLFIN boundary indicators from Netgen? I didn't
> >>> know.
> >> It is definitely possible :) I don't have direct converter from Netgen 
> >> vol to Dolfin xml. Most of my old models were stored in Diffpack grid 
> >> format, so I'm using grid to xml converter.
> >> Netgen can export to the grid format, so this is not a big issue.
> > 
> > It is not possible to store the boundary indicators in Dolfin format
> > using Netgen, at  the current time. I wrote the Netgen -> dolfin filter
> > in Netgen so I should know :).  
> > 
> > But it should be possible to include support for that in a similar
> > fashion as we did in VMTK. 
> 
> You are right that Netgen doesn't support Dolfin XML mesh format. But it 
> doesn't mean that is not possible to use boundary indicators generated 
> by Netgen in Dolfin. Converterting via Diffpack grid file preserves 
> boundaries.
> 
> The algoritm is simple:
> 1. Generate mesh using Netgen.
> 2. Mark boundaries indicators.
> 3. Export to Diffpack format.
> 4. Convert Diffpack to XML.
> 5. Enjoy boundary indicators in Dolfin.
> 
> cheers,

Nice, but not optimal. At some point, we need an application that can
do all of these (and more). There seem to be a couple of different
options:

  1. Extend Netgen with full support for DOLFIN (and change the toolkit...) 
  2. Extend Gmsh with full support for DOLFIN (and change the toolkit...)
  3. Extend MeshBuilder to do mesh generation (using for example Netgen)
  4. ?

Any thoughts on these options?

The problem with (3) is that no one is really developing MeshBuilder,
except when we pay Kalkulo (http://simula.no/applications/kalkulo/) to
do it.

-- 
Anders

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