[Nek5000-users] Rayleigh example - no flow development

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

Hi Simon,

Breaking the symmetry is indeed a good idea in general. Although, at high Rayleigh numbers this is not entirely necessary in my experience. I typically don’t add any perturbations.

I noticed a small typo in userf: “ffz = bouy”, not “ffz = buoy”.

Also, you load a restart file in the .rea file. This will overload the initial conditions, T=-z, you have originally specified in useric.

Regards,
Gijs

On 08 May 2015, at 05:23, nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> wrote:



Hi Simon,

It's usually a good idea to break symmetry in some way in order to get the flow
to start moving.  Usually that's done in useric by calling some type of random
number generator to put small amplitude disturbances into the field.

Paul

________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov<mailto:nek5000-users-bounces at lists.mcs.anl.gov> [nek5000-users-bounces at lists.mcs.anl.gov<mailto:nek5000-users-bounces at lists.mcs.anl.gov>] on behalf of nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> [nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>]
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To: nek5000-use.
Subject: [Nek5000-users] Rayleigh example - no flow development

Dear all neks,

Recently I have tried to modify the rayleigh example to my case. However, I discovered that no flow field is developed after a long time. All velocities are zero. I guess I miss something important in the example. Anyone knows which part of the code could lead to this?

Also, although I start with T = -z, I got asymmetric initial condition, something not as I specified as viewed in postnek. Did I miss any point in the .rea and .usr? The files are attached here. They are modified rea and usr from rayleigh to my case.

Thank you very much.

Regards,
Simon
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