[Nek5000-users] Small random perturbations

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

Dear Ali,


I've had good luck for rapid transition to turbulence in pipes with the attached i.c. routine.


In addition to random perturbations, it has a significant amount stream wise vorticity near the pipe wall that is rapidly stretched by the mean shear profile, so it generally takes off fairly quickly (e.g., within 10 convective time units).


Alternatively or in conjunction with this, you can start with a high Reynolds number and then reduce the Re once turbulence has set in.


hth,

Paul


________________________________
From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
Sent: Tuesday, March 6, 2018 10:09:35 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Small random perturbations


Thank you for responding. It is axisymmetric with periodic conditions at the ends.



what geometry are you interested in?
Philipp

On 2018-02-20 15:20, nek5000-users at lists.mcs.anl.gov<https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users> wrote:
>
> Hello everyone,
>
>     I am just wondering about the validity of my way to initiate
> turbulence. My question is that instead of introducing random
> disturbances to the initial velocity, can I introduce them to the
> pressure gradient? Hint, I am using Nek5000 to simulate statistically
> non-stationary turbulent flow.
>
> Thank you in advance
> Ali
> Embry-Riddle Aeronautical University

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