Upper limit on celerity value in diffusive Fortran kernel

[kumdonoaa]

Too high values of the celerity in the diffusive Fortran kernel often lead to too small (sometimes several orders of magnitude smaller than on second), which virtually freezes the kernel. To prevent it from happening, upper limits on celerity are placed after deriving from the Courant condition with minimum simulation time increment being initially given time step divided by an user-provided numeric value (10 in this case).

Additions

diffusive.f90: Once validated, the user-provided numeric value, for better use, should be directly passed from config yaml or through diffusive_util_v02.py

Removals

Changes

Testing

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• Windows
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• Is useable without CSS
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