[Nek5000-users] Linearised Navier-Stokes: 2D cylinder flow

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

Hi JC,

Are you trying to look at the perturbation from the
steady cylinder base flow ?

Am curious about your boundary conditions (though I
recognize that your bc set for the external cylinder
flow shouldn't be too different from the boundary
layer case)...

Just inquiring to get a better idea of what's going on.

Paul


On Wed, 5 Feb 2014, nek5000-users at lists.mcs.anl.gov wrote:

> Hi Nek's,
>
> I am trying to run a linearised DNS of the flow over a two-dimensional
> cylinder at Re=60 for illustration purposes using the ext_cyl example. I am
> however encountering some troubles... I have been able to compute the
> unstable steady equilibrium using a selective frequency damping approach
> without any trouble. However, it is quite a different story when it comes
> to the linearised DNS. Indeed, the perturbation velocity field blows up
> quite rapidly and I am not sure why. I have tried other flows (lid-driven
> cavity, boundary layer, ...) just to make sure I had no problem with  my
> nek install and everything was running fine. I have also tried on three
> different computers to make sure it was not platform-dependent and it
> actually blew up every time. I have been using the linearised version of
> nek quite extensively for the past three years and but never had such
> problem.
>
> Is there something I have missed there?
>
> Thanks a lot,
> JC
>
> -- 
> Jean-Christophe Loiseau
> Homepage <https://sites.google.com/site/loiseaujc/>
>