[Nek5000-users] ON boundary condition

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

Hi

Simpson is periodic in sreamwise direction so the fringe is needed. I
will add fringe to my run and test dependence on the box size.
Regards

Adam

On Thu, 2012-02-16 at 04:15 -0600, nek5000-users at lists.mcs.anl.gov
wrote:
> Hi Adam,
> 
> What BC do you use for Simpson?  Can you use the same for nek?
> 
> I would assume some sort of sponge condition would be warranted.
> I personally like the div > 0 condition, which works well for
> turbulent outflow, but I've not tested it extensively for the
> issues that you are having.  I'm guessing you might have more
> luck with the std. sponge approach.  Please let me know if I
> can help, though I think that most of the sponge expertise is
> there in your lab.
> 
> Best regards,
> 
> Paul
> 
> 
> On Thu, 16 Feb 2012, nek5000-users at lists.mcs.anl.gov wrote:
> 
> > Hi Paul
> >
> > Thank you for info. I'm using ON at the top of my box for jet in
> > crossflow (it was originally in the setup I've got from Milos and I
> > simply didn't change it) and it seem to work fine (I use Pn-Pn-2). My
> > bigger problem is an outflow. I'm using O, but in many cases it gives
> > reflections that trigger spurious oscillations, so I was looking for
> > something better. To avoid this problem I run my simulations in the long
> > box with an outflow 150 away from the pipe. It's a lot comparing to 60
> > in simson. Every run with the distance smaller than 100 gives
> > nonphysical solutions. Is there in nekton some good non reflecting
> > boundary condition?
> > Best regards
> >
> > Adam
> >
> > On Wed, 2012-02-15 at 08:33 -0600, nek5000-users at lists.mcs.anl.gov
> > wrote:
> >> Hi Adam,
> >>
> >> I set up ON bc some years back to support Blasius boundary layer
> >> analysis in which the tangential (streamwise) velocity is
> >> prescribed and the wall-normal velocity is allowed to escape
> >> as the velocity boundary layer thickens.  This also implies
> >> that the pressure is fixed on the upper surface.   This feature
> >> was developed  for Pn-Pn-2 and hasn't been extensively tested
> >> in many years.   If this is a feature that you need, we could
> >> look into resurrecting it.  (Note that the "escaping" feature
> >> implies that the surface is aligned with either x,y, or z, and
> >> not inclined w.r.t. these principal axes.)
> >>
> >> Cheers,
> >>
> >> Paul
> >>
> >>
> >>
> >> On Tue, 14 Feb 2012, nek5000-users at lists.mcs.anl.gov wrote:
> >>
> >>> Hi all
> >>>
> >>> I try to find some information about ON boundary condition in nekton.
> >>> What is the difference between O and ON?
> >>> Regards
> >>>
> >>> Adam
> >>>
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