Re: [Libmesh-users] Adding a force to a boundary through an additional node

[Renato P. <re...@gm...>]

Hi, thanks for the answer:

@edgar: it is a FORCE (Neumann) while DISPLACEMENTS (primary variables)
must be tied together. (I am trying to solve Mandel's problem in
poroelasticity). Please let me know if it is clear.

@Vikram: I did not get exactly the use of the SCALAR variable. It is a
single value in the whole domain, is that correct? Should I add this
variable _only_ in the boundary domain? I am digging into the
systems_of_equations_ex3, let's see if it gets clearer in the next few
days.

Thanks,
Renato

On Sun, Jun 27, 2021 at 8:38 PM Vikram Garg <vik...@gm...> wrote:

> You might need a Lagrange multiplier formulation that sets a state variable
> in an entire subdomain or boundary to a single unknown scalar. Example 3 in
> systems of equations might help, it shows how SCALAR variables can be used.
> You could incorporate the scalar variable into the weak form via a penalty
> method.
>
> Vikram Garg
>
> vikramvgarg.github.io/
>
>
> On Sun, Jun 27, 2021 at 6:10 PM edgar <edg...@cr...> wrote:
>
> > On 2021-06-27 23:01, Renato Poli wrote:
> > > I'd like to add a force to a whole boundary. The constraint is that the
> > > whole boundary must have the same displacement.
> > > ---8<--- snip
> >
> > For the sake of disambiguation: do you want to impose displacement or
> > force? The displacement of a boundary is not only dependent on the force
> > it receives.
> >
> > I am guessing that the developers (regular user here! hi!) would like to
> > know.
> >
> >
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