Fill out auto-averager with a short usage case

[lcarasik]

Specifically, usage of the autoaverager subroutine and the best way to handle averaged field files in different subdirectories.

Below is compiling the information to help with this from the user forms.

https://lists.mcs.anl.gov/pipermail/nek5000-users/2017-November/004814.html

"Hi ZJ,

A quick search of the archives with keyword “avg_all” will give you answer to related questions:
https://lists.mcs.anl.gov/mailman/mmsearch/nek5000-users?config=nek5000-users.htsearch&restrict=&exclude=&method=and&format=short&sort=score&words=avg_all

avg_all is a collection of time-averaged information in the avg, rms and rm2 files. The avg files has time-averaged u,v and w; rms has time-averaged u^2, v^2 and w^2; and rm2 has uv, vw, and uw. The avg_all routines is located in navier5.f in case you want to get more information.

Typically the first step in post processing is to use the routine “auto_averager” to combine all the files output from avg_all. autoaverager takes as input the name of a file (example: fname1.list) which has a list of all the files that you want to combine (example: the contents of fname1.list will be: avgcasename0.f00001 avgcasename0.f00002 … Note- there should be only 1 filename per line in the fname1.list file). You can use the auto_averager routine to combine all your avgcasename0.f00* files and output them to a single file or do more post-processing with it. The quantities available in avg, rms and rm2 files are sufficient to get the actual urms, vrms velocities etc… Additionally, once you time-average the data using auto_averager, you can use space averaging routines such as z_avg etc… to average quantities in homogeneous direction of your domain.

It would also help if you specify what exactly are you trying to get from these avg_all files i.e. are you looking for rms velocities or something else?

Here is a snippet of my code that I have used in the past to post-process these files:
call auto_averager(fname1)
call copy(uk,vx)
call copy(vk,vy)
call copy(wk,vz)
call col2(uk,uk,lt)
call col2(vk,vk,lt)
call col2(wk,wk,lt)
call auto_averager(fname2)
call sub2(vx,uk,lt)
call sub2(vy,vk,lt)
call sub2(vz,wk,lt)
call z_avg(vxa,vx,gs_avg_hndl,nelxy,ifld)
call z_avg(vya,vy,gs_avg_hndl,nelxy,ifld)
call z_avg(vza,vz,gs_avg_hndl,nelxy,ifld)
call outpost(vxa,vya,vza,vxa,vya,' ')

Here fname1 has the list of all avgcasename0.f00* files and fname2 has the list of all the rmscasename0.f00* files.

Additional Discussions:

https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2018-February/005017.html
https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2018-July/005469.html
https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2017-October/004694.html - for turbulent heat fluxes