[Nek5000-users] Questions regarding avg_all

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

Usually I just build a sequence of files with a different name such that the first one has the geometry.  This is easily done with a unix script, e.g.:


ln case0.f00001   view0.f00001

ln avgcase0.f00001 view0.f00002

ln avgcase0.f00002 view0.f00003


etc.


Then use visit to look at case "view"


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: Sunday, February 4, 2018 2:08:08 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Questions regarding avg_all

Hi Phillip,

Thanks for the reply, that was very clear. However, I'm now facing a problem while trying to load the avvgblah.f000* files from my case. Currently I'm running visnek on these averaged files, generating a .nek5000 file and trying to read that using visit or paraview. This procedure results in an error. The reader complains that the first step of a nek file must contain a mesh which the files generated by avg_all do not seem to have. What is the procedure for reading this data then?


Sincerely,

On Sun, Feb 4, 2018 at 5:39 AM <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>> wrote:
Dear Amitvikram,

As far as I understand, the basic version of avg_all perform only a time
average, i.e. the statistics are computed in 3D in every point of the
domain. In case your flow has additional directions of homogeneity, then
one can do an average over those directions as well; either by taking
the output of avg_all and doing the average there, or direction during
runtime (for the latter there is an implementation described here:
http://www.ipd.anl.gov/anlpubs/2017/03/133610.pdf)

Best regards,
PHilipp

On 2018-02-03 17:36, nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> wrote:
> Hi all,
>
> I understand that a call to avg_all computes the running averages of u,
> u^2 etc and then dumps the results after a fixed timestep as given by
> param68.
>
>   What I do not understand is where in the domain does this computation
> take place? Does it average all the points in the domain? I understand
> how this would by useful in the turbChannel case where fully developed
> turbulence covers essentially the entire domain. However in cases where
> the flow develops turbulence within the domain and thus there are strong
> regions of turbulent anisotropy, it would be imperative to calculate
> these running averages along a specified plane or line. I did see some
> code defining these in the turbChannel example
> viz. common /plane/  uavg_pl(ly1*lely)
>       $             ,  urms_pl(ly1*lely)
>       $             ,  vrms_pl(ly1*lely)
>       $             ,  wrms_pl(ly1*lely)
>       $             ,  uvms_pl(ly1*lely)
>       $             ,  yy(ly1*lely)
>       $             ,  w1(ly1*lely),w2(ly1*lely)
>       $             ,  ffx_avg, dragx_avg
>
>
> but I'm not exactly sure how this is defining a particular section of
> the geometry. In my particular case I'm trying to simulate a rectangular
> jet exhausting into a cuboidal domain. How can I set avg_all to compute
> the said average along a streamwise plane of the jet for example?
>
> Sincerely,
> --
>
> *Amitvikram Dutta*
>
> Graduate Research Assistant
>
> Fluid Mechanics Research Lab
>
> Multi-Physics Interaction Lab
>
> University of Waterloo
>
>
>
> _______________________________________________
> Nek5000-users mailing list
> Nek5000-users at lists.mcs.anl.gov<mailto:Nek5000-users at lists.mcs.anl.gov>
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>
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--

Amitvikram Dutta

Graduate Research Assistant

Fluid Mechanics Research Lab

Multi-Physics Interaction Lab

University of Waterloo
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