[Nek5000-users] Problem with the number of iterations

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

You can try setting the divergence and helmholtz tolerances to zero in the
.rea file.
Then nek will automatically estimate reasonable tolerances based on the
settings
that you currently have for tolrel.
Given that your inflow and chord are not 1, this might be a good idea.
There is nothing intrinsically wrong with an iteration count of 1, however.

Paul


On Wed, Dec 5, 2018 at 12:34 AM nek5000-users--- via Nek5000-users <
nek5000-users at lists.mcs.anl.gov> wrote:

> For this geometry, I tried the low Re (~10^3), but the number of
> iterations for the velx, vely, velz also did not exceed 1. What do you
> think? Why do I have the same number of iterations for the low Re?
>
>
> Вторник, 4 декабря 2018, 19:56 +07:00 от nek5000-users--- via
> Nek5000-users <nek5000-users at lists.mcs.anl.gov>:
>
>
> Your problem has very low viscosity, so there will be very few velocity
> iterations.
>
> I would suggest turning off the filter if it's not helping -- but most
> likely
> there is another issue (e.g., perhaps needing more resolution for the
> target Reynolds
> number).
>
> For a wing, it might not be a bad idea to first run a 2D airfoil at the
> target conditions
> just to get an idea of the meshing requirements for the target Re.
>
> hth,
>
> Paul
>
>
> On Tue, Dec 4, 2018 at 6:21 AM nek5000-users--- via Nek5000-users <
> nek5000-users at lists.mcs.anl.gov
> <https://e.mail.ru/compose/?mailto=mailto%3anek5000%2dusers@lists.mcs.anl.gov>>
> wrote:
>
>
> Hi, Neks!
> I am working with a complex geometry which was built in gambit. I have
> some questions.
> 1) When I start Nek5000, I have only 1 itteration for velx, vely,velz, but
> for the preassure field itterations >30. How can it be possible?
> 2) When I set p103=0.1 in .rea file, Courant number increases and becomes
> >1 very fast. How does the filtration effect on the Courant number?
> I attached my .rea file and  logfile.
> https://drive.google.com/open?id=1YEV2f5Mllqenhu-rk39YJ84_1XHYjC_H
>
>
> *https://drive.google.com/open?id=1jRKI_zEnb78cR7uXFi3mE0txk6FN3EXQ
> <https://drive.google.com/open?id=1jRKI_zEnb78cR7uXFi3mE0txk6FN3EXQ> *
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