Re: [Getfem-users] Dirichlet BC in vectorial problems

[Yves Renard]

Le Jeudi 19 Avril 2007 14:47, Andriy Andreykiv a écrit :
> Dear Yves and Jullien,
>
>   Would you please advice me on the following.
>
>       If I have a vectorial problem like liniear elasticity, how can I 
> prescribe
> only one component of the displacement vector on a given boundary?
> I don't see how I can do this with Dirichlet Brick or
> assembling_Dirichlet_condition, as they both with prescribe the value of
> all the components of the displacement.
>
>       Another question if I may. Is there a possibility to prescribe a 
> Dirichlet
> boundary condition on a node, not a face of the element. Somtimes it is
> necessary to prevent rigid body modes in mechanical problems, while
> constraining a face will change the physics of the problem.
>

Hello Andriy,

There is in fact some bricks (not documented I think) dealing with for 
instance the normal component (mdbrick_normal_component_Dirichlet, see 
getfem_modeling.h). For more particular things, you should adapt either this 
brick or the Dirichlet brick itself. If you tell me exactly what you need, i 
can help you.

If you need to prescribe a value of a specific d.o.f., you can use directly 
the constraint brick (see the documentation). You need of course to locate 
the corresponding d.o.f. number and creat an adapted constraint matrix.

Yves.

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  Yves Renard (address@hidden)       tel : (33) 04.72.43.80.11
  Pole de Mathematiques, INSA de Lyon          fax : (33) 04.72.43.85.29
  Institut Camille Jordan - CNRS UMR 5208
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  http://math.univ-lyon1.fr/~renard
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