Output field numbering and firsttimetep in visnek

[timofeymukha]

Killed quite a bit of time on the following. Having generated some solution data in field files, I was using the Nek5000 utility visnek to create a .nek5000 file to open in Paraview. However, this would not work, both Paraview and Visit threw an error. Finally, I realized that the issue was that the first output is field0.f00000, but Paraview expected it to start with 1, i.e. field0.f00001. This can be controlled by setting firsttimestep: 0 in the generated .nek5000 file.

Can one somehow make this work right automatically? Mabe one can pass firsttimestep as a parameter to visnek? Or should we just create visneko, which defaults this to 0? I guess, that anyway we should not rely on a nek5000 utility.

[njansson]

Hmm, didn't the .nek5000 file that Neko spits out work directly?

[timofeymukha]

I did not realize neko creates its own .nek5000 :). It was a productive 2 hours today.

[pschlatt1]

Halfways related: the first file written out when setting nsamples is not at the initial time. Would it be useful to have a flag to write out the intial field as well, e.g. to check the initial conditions from user_ic? This would then mean that one perhaps should reserve field0.f00000 for that, and start the normal numbering at field0.f00001. to field0.f0nsamples.

[timofeymukha]

Sounds like a good idea.

[njansson]

Not sure, but isn't this what PR #644 adds?