dolfin team mailing list archive

[Kent Andre <kent-and@xxxxxxxxx>]

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. 

> 
> > Meshing is a problem for us. I don't know what the long-term goal
> > is. Netgen is good but it would be nice if the interface could be
> > updated to a modern toolkit instead of Tk.
> 
> True. Netgen is good mesher, but its development stopped several years 
> ago. Few months ago Joachim registered sf.net project, so there are 
> chances for new activity,
> 
> > One option could be to add meshing capabilities to MeshBuilder (using
> > an external library like Netgen).
> 
> This shouldn't be difficult to do. Of cource it depends how strong 
> integration you need.
> 
> > I'd like a tool where I can
> > 
> >   1. draw simple domains in 2D / 3D
> 
> Simple modeler/CAD ?
> 
> >   2. import CAD geometry
> 
> I recommend to use STL as portable format.
> 
> >   3. set boundary indicators
> 
> Netgen has such feature.
> 
> >   4. create and export Mesh in DOLFIN XML
> 
> Set of converters can solve this problem.
> 
> 
> 
> 
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