[Nek5000-users] ON boundary condition

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

Hi Adam,

Yes -- but you could of course run nek with periodicity in
the streamwise direction, if that is what makes the difference.

Paul




On Thu, 16 Feb 2012, nek5000-users at lists.mcs.anl.gov wrote:

> 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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