[Nek5000-users] neuman bc for the normal velocity component

[nek5000-users at lists.mcs.anl.gov]

Hi Joris,

The usage you describe should work.

I've put an example "blasius" in the examples directory.

Note that a common failure mode is where fluid is drawn _in_
to the domain through the ON boundary.  This can happen if
the pressure is such that flow wants to come in rather than
leave.

However, from what you describe, it sounds as if something
else is going wrong in your case.  Perhaps looking at the
example will help.

Paul


On Thu, 20 Sep 2012, nek5000-users at lists.mcs.anl.gov wrote:

> Dear Nekians,
>
> I'm relatively new to nek.
>
> I would like to
> compute the flow of a boundary layer and
> I would like to impose the following
> boundary condition on the top (2D) boundary,
> which is parallel to the wall:
>
> u = U_base and dv/dy = - dU_base/dx,
>
> where U_base is the known inviscid base flow.
> The velocity component u is parallel to
> the boundary, whereas v is normal.
>
> I tried to use 'ON ' but this did not give
> the result I was expecting (Am I doing smth. wrong?).
> At the boundary nodes u was equal to U_base, but
> at the very next node u was completly different
> (and v was of course completly wrong).
>
> Thanks for any help
>
> Joris
> _______________________________________________
> Nek5000-users mailing list
> Nek5000-users at lists.mcs.anl.gov
> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>