[Nek5000-users] Restart problem

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

Hi Adam,

Are you using pn/pn ? or pn/pn-2 ?  (I'm guessing the latter?)

I've not yet got this thing fully resolved, but one issue appears
to be an inaccuracy when mapping back and forth from N-2 to N.
This is only used for restart and should not be an issue since the
information originates on N-2 --- there should be very little
loss, save for the conditioning of the interpolation matrices.
I'm presently seeing more, and will fix this issue.  Also, I think
we'll go to a loss-less conversion for the particular case of
restarting with 8 bit precision.

That being said, there is something else that remains to be tracked
down given that pn/pn restart also has issues.   Still digging...

Paul


On Thu, 8 Dec 2011, nek5000-users at lists.mcs.anl.gov wrote:

> Hi Aleks
>
> Yes, I did. It's described in prepost.f and I implemented it in my usr
> file. Unfortunately my case so sensitive it doesn't help.
> Regards
>
> Adam
>
> On Wed, 2011-12-07 at 11:01 -0600, nek5000-users at lists.mcs.anl.gov
> wrote:
>> Hi Adam,
>>
>> Have you tried the full restart option described in email
>>
>> https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2010-August/000900.html
>>
>> There was an earlier email about some problems with it -- I can check it once I came back from travel.
>>
>> Best.
>> Aleks
>>
>>
>> ----- Original Message -----
>> From: nek5000-users at lists.mcs.anl.gov
>> To: nek5000-users at lists.mcs.anl.gov
>> Sent: Tuesday, December 6, 2011 8:23:37 AM
>> Subject: [Nek5000-users] Restart problem
>>
>> Hi
>>
>> I simulate jet in crossflow problem with nek5000 and I've got serious
>> problems with restarting the simulation. It causes strong spurious
>> velocity oscillation and I cannot get rid of them. I've implemented
>> restarting procedure described in prepost.f, but it doesn't help much.
>> Playing with file format (parameters p66, p67) and projection (p94, p95)
>> I can only decrease oscillations amplitude, but they are still there.
>> Surprisingly saving output files in double precision (p63=8) makes
>> everything worse. Has anybody got similar problems?
>> Best regards
>>
>> Adam
>>
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