[Nek5000-users] CFL's impact on data & 3D without .rea

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

Hello NekGurus,

I have been studying Nek5000 this summer as part of a project investigating it's viability as a replacement/alternative to other commercial codes.  My two test cases, natural circulation & convective pipe flow, are producing nice results with the only issue being a 'WARNING: DIV(V)-QTL too large!'  after X time steps.  I've increased my targetCFL, from 0.4 to 4.0, and changed dt from variable to fixed.  This has eliminated the warning, at the cost of a longer runtime.  My first question is; will the changes to the CFL value effect the accuracy of temperature or velocity results?
Second, I would like to expand one (or both) of the cases to 3d, do I need to create .rea file to do this, or is it better to import a 3d .STEP file?  I've tried using n2to3 and re2torea, but the later outputs the following:

'At line 70 of file re2torea.f
Fortran runtime error: End of file.'

With an empty .rea file.

It is my impression that the .rea file is no longer necessary.  Is this incorrect?  Please advise on the best way to proceed.

Thank you very much,

Mario

Mario R. Naranjo

Computational Sciences and Engineering
Los Alamos National Laboratory
naranjom at lanl.gov<mailto:naranjom at lanl.gov> | W: 505-664-0978 | M: 505-980-4187

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