Re: [Getfem-users] combining 2D and 1D elements]

[Yves Renard]

Dear Till,

You can indeed mix into the same mesh 2D and 1D elements. But you cannot 
affect a 1D finite element method directly on the boundary of a 2D element. 
You have to add explicitely the 1D element first to the mesh.
If you use Lagrange elements, the correspodance between the dof of 1D and 2D 
elements will be taken into account correctly.

Of course, this means that you will have a PDE solved in your 2D domain and 
also a PDE on the boundary of your domain.

Yves.

On lundi 22 février 2010, Till Heinemann wrote:
> Hello!
>
> I'm pretty new to this library and I would like to do the following:
> Implement a 2D domain (mesh) with standard lagrange elements plus 1D
> lagrange (with bubble function) elements on this domain's boundary!
>
> Could I somehow do this on one mesh (compiler says no),
>
> Incompatibility between fem FEM_PK_WITH_CUBIC_BUBBLE(1,1) and mesh
> element GT_LINEAR_QK(2)
>
> and if not, is there later for the assembly of the system description an
> easy way to know which node-dofs interface at the same spacial position
> (i.e. without looping twice and checking their positions / thus writing
> a connection table of some sort)? I mean, the elements need to know that
> they have an existing neighbor (on a different mesh).
> Also, I don't see yet how to write a mesh from a mesh_region (i.e.
> boundary), but I'm sure I'll figure that out sooner or later.
>
> Now I thought there must be a standardized way for this, as I read in
> http://download.gna.org/getfem/doc/getfem_project/getfem_project_5.html#id9
> connecting neighboring elements of different dimensions is already
> implemented?
>
> Thank you for any suggestions on which methods or types that might help
> me,
>
> best regards
> Till
>
>
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-- 

  Yves Renard (address@hidden)       tel : (33) 04.72.43.87.08
  Pole de Mathematiques, INSA-Lyon             fax : (33) 04.72.43.85.29
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  http://math.univ-lyon1.fr/~renard

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