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

[sébastien janas]

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
> >
> 
> 
> 
>