Re: [Getfem-users] How to impose the normal derivative to zero on a model ?

[Ronan Perrussel]

Dear Sébastien,

Yves' answer to your question is that you have nothing to do (nothing at 
all... it is implicitly taken into account in the weak formulation).

Best regards,
Ronan

sébastien janas a écrit :
> Thanks a lot,
>
> So, the best is to use the function
>
> add_normal_source_term_brick
>
> on my boundaries with data a vector [ 0,0,0 ] ?
>
> something like this
>
> md.add_initialized_fem_data('WALL', mf, np.repeat([0,0,0],nbdof))
> md.add_normal_source_term_brick(mim,'P','WALL',10)
>
> 10 is the tag of the boundaries.
>
> Sorry to disturb you for such trivial things ;-)
>
> Best regards,
>
> Sébastien
>
>
>
> Le jeudi 08 avril 2010 à 09:46 +0200, Yves Renard a écrit :
>   
> > Dear Sebastien,
> >
> > No of course. For an order two isotropic pde, a homogeneous Neumann condition 
> > reads as
> > dU/dN = 0
> > This condition does not add any term to the weak formulation. So you do not 
> > have to add anything to the model.
> >
> > Yves.
> >
> > On mercredi 7 avril 2010, sébastien janas wrote:
> >     
> > > Dear Yves,
> > >
> > > When we prescribe a zero neumann condition, we impose that the product
> > > between the unknown and the normal vector is equal to zero, is it equal
> > > to assume that the product bewteen the GRADIENT of the unknown and the
> > > normal vector is equal to zero ?
> > >
> > > In other words, you advise me to do
> > >
> > > n x U = 0
> > >
> > > and I want to do
> > >
> > > dU/dn = 0
> > >
> > > is it equal ?
> > >
> > > Best regards,
> > >
> > > Sébastien
> > >
> > > Le mercredi 07 avril 2010 à 21:12 +0200, Renard Yves a écrit :
> > >       
> > > > Dear Sebastien,
> > > >
> > > > If you have to prescribe a zero Neumann condition to your unknown
> > > > (assuming that it is an order two isotropic pde), you
> > > > do not have to add anything to your model. This is somehow a default
> > > > boundary condition as it add nothing to the weak formulation.
> > > >
> > > > Yves.
> > > >
> > > > sébastien janas <address@hidden> a écrit :
> > > >         
> > > > > hi,
> > > > >
> > > > > I am using the python interface of getfem. I want to impose the normal
> > > > > derivative of my unknow to zero at the boundary, but it seems that the
> > > > > model method "add.normal_derivative_source_term" don't exist, is it
> > > > > correct ? If yes, what's the best way to impose such a condition on a
> > > > > model ?
> > > > >
> > > > > Thanks a lot for your help,
> > > > >
> > > > > Sébastien
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > Getfem-users mailing list
> > > > > address@hidden
> > > > > https://mail.gna.org/listinfo/getfem-users
> > > > >           
> >
> >     
>
>
> _______________________________________________
> Getfem-users mailing list
> address@hidden
> https://mail.gna.org/listinfo/getfem-users
>

ronan_perrussel.vcf
Description: Vcard