[Nek5000-users] SYM boundary conditions

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

Hi,
SYM is essentially means that the velocity through the interface is zero 
and for the inplane velocities that the normal gradients vanish. So it 
does not allow transpiration/penetration through the boundary. So I 
suspect that this condition is not what you are looking for.

However, I am not exactly sure what you really mean. Perhaps you can say 
a bit more about your case?

Best regards,
Philipp

On 2016-02-10 08:02, nek5000-users at lists.mcs.anl.gov wrote:
> Hi Neks,
>
> I am looking for a boundary condition that leads the flow to go out or
> to go into the domain.
>
> Is 'SYM' valid for this purpose?
>
>
> I think that what I am looking for is, in the outlet surface:
>
>    - If the velocity vector at the outlet points out of the domain, then
> the boundary condition for the velocity will be of the Neumann type
>
>    - However, if the velocity at the outlet points into the domain, then
> we can imagine that the outflow is no longer an outflow, but an inflow,
> and that we therefore would like to specify a Dirichlet boundary
> condition for velocity
>
>
> Thanks in advance
> SL
>
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