[WIP]feature_coolprop thermodynamics model

[PENGYAN777]

Proposed Changes

This project aims to couple the free and open-source thermodynamics library CoolProp with SU2.

There are two advantages:

1. More accurate numerical results.
   CoolProp can provide accurate thermodynamics properties (P, T, rho, ect) of commone fluids by either extracting experiment data from published papers, or computing based on the state-of-the-art Helmholtz energy formulations.
   So, thermodynamics properties obtained from CoolProp should be more accurate than those obtained from Van der Waals or peng robinson gas model embedded in SU2. Also, the numerical results should be more accurate.
2. More user-friendly
   To use CoolProp feature, the ony input from the user is the name of fluid. Then all other thermodynamics can be provided by CoolProp.
   %FLUID_MODEL = COOLPROP
   %FLUID_NAME = nitrogen

Related Work

This project references the following work:
1.the work of coupling 'Mutationpp' with SU2.
4. the pull request of 'Feature nppr gas #1718'

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings.
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• Simulations with the following test fluids succeed: nitrogen, oxygen, carbon dioxide, MM.
• Currently, this new feature is applied for only Euler flow. For viscous flow, further work need to be done, including viscosity, conductivity from CoolProp.
• CoolProp does not support non-dimension.

[PENGYAN777]

Hi, I add an error if CoolProp is used with non-dimensionalization in CConfig::SetPostprocessing.

But when I try to run simulation with:
FLUID_MODEL = COOLPROP
REF_DIMENSIONALIZATION = FREESTREAM_PRESS_EQ_ONE

SU2 is running well.

Could you please help find the reason why the new codes in CConfig::SetPostprocessing. does work.

Thank you.