Telemac2d fv caldt

Description

Better time step management in finite volumes.

• Add new keyword ADAPTATION OF TIME STEP TO GRAPHIC PRINTOUTS, with default value to NO i.e. time step adaptation to graphic printouts is now optional in finite volumes.
• If NO results at tn+1 are written if tn<trec<tn+1;
• If YES the time step dtn is adapted so that tn+dtn=trec (old behavior);

Improvements of the caldt subroutine of finite volumes, which includes:

• allowed CFL > 0.9 (before is was forced to 0.9);
• warning if CFL > 1 with advised time step (CFL = 0.9);
• new sigmax zero avoidance (eps=1D-16 instead of 1D-2);
• correction of the second order time step limitation;
• lift VARIABLE TIME-STEP restriction in FV.

Checklist

All Merge Requests:

• Update NEWS.txt to describe your changes.
• Run compile_telemac.py --check to check FORTRAN coding conventions.
• Run pylint to check Python coding conventions.
• If you added new files, run compile_telemac.py --clean --rescan and commit the updated cmdf file(s) accordingly.
• Run compile_telemac.py --clean for both normal and debug configurations.
• Run validate_telemac.py for both normal and debug configurations.
• Run validate_telemac.py --notebook for both normal and debug configurations.
• Run doc_telemac.py if there are any modifications in the documentation.
• Run damocles.py --eficas if there are any modifications in the dictionaries.

In addition, for a new feature:

• Check that your feature works in both serial and parallel modes.
• Add at least one test case to check the functionality (with documentation, graphics and VnV script)
• Update the documentation for the module in which your feature will be available.