[Nek5000-users] Questions regarding avg_all

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

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
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