[Nek5000-users] Stability utilities

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

Hi Guillaume,

Thank you for clear my misunderstanding! I am not sure which exact the
numerical scheme adopted in nek5000 to solve the eigenfunctions of direct
and adjoint problems. I myself did not implement new things, just run a
steady cylinder flow supplied in cyl_restart and used the setups of
lin_chan2D to continue my simulation. I enclosed the parameter files here,
please check where I was wrong. Thanks!

Wei

On Mon, Feb 26, 2018 at 9:38 PM, <nek5000-users at lists.mcs.anl.gov> wrote:

> Hi,
>
> If I understand the lin_channel2D example correctly, it is not using any
> Krylov method but simply sets an initial perturbation and lets it evolve.
> Are you using the Arnoldi algorithm?
>
> I can have a look if you upload your files somewhere.
>
> Guillaume
>
>
> Le 24/02/2018 à 08:53, nek5000-users at lists.mcs.anl.gov a écrit :
>
> Dear Neks,
>
> Recently, I am trying to set up a linear stability analysis of flow past a
> cylinder at very low Re, see Re=20, after I had a converged base flow, I
> modified the example “lin_chan*” and read the dns result as baseflow and
> updated the *usr file, after testing groups of parameters in *.par, I
> obtained different groups of growth rates, but none of them is closed to
> the value documented by Luchini et tal, JFM or the value given by other
> codes. Are there more details or rules to choose the parameters when
> performing a linear stability, e.g. Krylov space dimension, number of
> converged eigenvalues to be dumped?
>
> Thanks!
> Wei
>
>
>
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-- 

Wei HE 何偉
School of Aeronautics
Universidad Politécnica de Madrid
http://www.cfm.upm.es/
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