dolfin team mailing list archive

[Andre Massing <massing@xxxxxxxxx>]

Den 22.02.11 09.52, skrev Garth N. Wells:
> On 22/02/11 07:51, Anders Logg wrote:
> > I'd like to implement this blueprint for 0.9.10:
> >
> > https://blueprints.launchpad.net/dolfin/+spec/attach-subdomains-to-form
> >
> > In addition, I'd like to remove the cell_domains,
> > exterior_facet_domains and interior_facet_domains arguments from the
> > assembler. It seems overkill to have three different ways to specify
> > the domains and the logic becomes complex for handling which data
> > overrides if many are specified. We could also remove these arguments
> > from VariationalProblem.
> >
> > We would then have two ways to specify the subdomains:
> >
> > 1. As part of the Mesh (MeshData)
> >
> > 2. As part of the form
> >
> > The SystemAssembler would then need to rely on (1).
> >
> > Comments and objections?

I use MeshFunction as domain markers quite a lot and it can be the case 
that you need some marking based on other, more complex decision 
procedures than just the virtual bool inside(...) function in subdomain.
For instances (of course the example must come from my side :) I used it 
heavily in overlapping mesh method. Forcing the use of subdomains would 
force the user to implement the possibly complex decision procedure for 
which cells, facets etc have to be marked within the SubDomain class, 
probably requiring some inheritance, with additional constructors which 
can take the needed extra arguments.

At least I would advocate for having the flexibility
to determine the actual subdomains (maybe could assign MeshFunctions to 
them?) and the possibility to change them, even after they have been 
assigned to a form (so not only const reference access).

--
Andre


> What's the advantage of having two methods? Why not just have one?
>
> I'd would be happy to see subdomains as part of MeshData, but I would be
> reluctant to use the existing data structures because I find them cryptic.
>
> We could have cell domains become part of the mesh .xml files - this
> would be helpful because mesh generators can often define domains, and
> it would be handy to use this data easily (by supporting it in
> dolfin-convert).
>
> Garth
>
> > --
> > Anders
> >
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--
André Massing       		email: massing@xxxxxxxxx
Ph.D. student			mobile: +47 469 57 401
Simula Research Laboratory
NO-1367 Fornebu, Norway