[WIP] Inconsistencies and improvements to SST model

[rois1995]

Proposed Changes

Hi everyone,

I have found some inconsistencies with respect to the literature on the implementation of the Menter's SST model. I would like to use this branch as test bench for any corrections/improvements made to the SST model.

Implementation errors found:

• Use of production limiter constant in the clipping of the cross-diffusion term for the computation of the F1 blending function in CTurbSSTVariable.cpp.
• SST naming conventions (V in V2003m should stay for Vorticity production term.). Not yet assessed.
• Wrong cross-diffusion term included into the residual of w in turb_sources.hpp. It should not be only the positive value as considered in the computation of the F1 blending function. As stated in https://doi.org/10.2514/3.12149. "CDkw is the positive portion of the cross-diffusion term in Eq (A2)" pag. 1604. Moreover, a clipping has been introduced for large negative values of this term, as suggested in Peng, Shia-Hui, Peter Eliasson, and Lars Davidson. "Examination of the shear stress transport assumption with a low-Reynolds number k-omega model for aerodynamic flows." Eq 17.
• Boundary conditions errors at inlets, following the Issue #1851. A fix has been proposed following @pcarruscag suggestions for the supersonic inlet BC.
• Boundary conditions definitions are different than the ones proposed in TMR. Maybe give the user the choice to use the BCs implemented in SU2 or the ones from TMR.

Changes to SST model proposed:

• Inclusion of non modified versions of SST. In this case I think that more work is needed to be sure that the correct terms are taken into account everywhere in the code.
• Give the user the possibility of changing the production limiter for TKE (not essential).
• Change values of default turbulent to laminar viscosity to 1e-2 (NASA TMR reports that it should be in the range of 1e-2 to 1e-5, but in SU2 this is set to 10 as default).

I've seen the proposed changes to the lower limits of k and w in #2323 and I tried implementing it in my branch. However, if the implementation proposed in the respective PR is preferred then I will change mine.

Related Work

#2323 #1851

PR Checklist

Put an X by all that apply. You can fill this out after submitting the PR. If you have any questions, don't hesitate to ask! We want to help. These are a guide for you to know what the reviewers will be looking for in your contribution.

• [X] 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 used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• [ ] 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.