Corrections to SA-NEG-R and SA model

[rois1995]

Proposed Changes

Hi, I found some problems with the implementation of the SA-NEG and SA-NEG-R models wrt to what is described on TMR. Plus, I found a suggestion on the computation of the SHat variable to avoid clipping for negative values (also reported on TMR).

Related Work

• Implementation of new computation of SHat (Jacobian was computed by hand and is somewhat complex. Probably I could derive a simplified formulation)
• Added CRot constant for SA-R model
• Modified computation of var.S for the combination SA-NEG-R
• Slightly change the computation of muT from nu_tilde: now muT = 0 if nu_tilde <0. Before it was muT = max(muT, 0.0), which should not always coincide with nu_tilde > 0.
• Not related to SA: added viscous drag as output in the history file.

I should also try to add the maximum value of nu_tilde within the mesh to the history file, although I still have to implement it.

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.

[pcarruscag]

Can you guys wrap this up and update the required restart files?
I want to make the fixes to the SST model we want for v8.

[rois1995]

@pcarruscag Sorry for the delay. Which restart files are you referring to?

[pcarruscag]

Some of the testcases that show as failed need to be updated, if the update is significant for cases with restart files we need a new restart file to match the previous convergence level.

[bigfooted]

I just updated the serial and parallel regression tests. There is one SA test that has a restart file, I will also update that one.
@rois1995 can you have a look at the failed cases for the tutorial.py and vandv.py regression tests? I will have a look at the *_AD.py regressions this Friday.

[rois1995]

@bigfooted sure, I'll look into it right now.