Simplify Molar Mixture Properties

[ischoegl]

Changes proposed in this pull request

There are some instances where ThermoPhase objects use redundant code for the evaluation of molar mixture properties.

This PR seeks to provide a more uniform approach to evaluating molar properties. By default, average properties should be calculated as a weighted sum, e.g. $\bar{h} = \sum X_k \bar{h}_k$. getPartialMolar<> getters are used to obtain partial molar properties.

• default behavior for molar mixture properties is changed to summation rather than throwing an exception
• improve exception handling for any virtual ThermoPhase method that is not implemented
• redundant/equivalent overrides are removed unless speed advantages are apparent

One caveat is that this approach has limitations for intEnergy_mole and cv_mole. These properties are implemented differently as they are largely based on simplified thermodynamic relationships rather than summations. Interestingly, an attempt to base intEnergy_mole on getPartialMolarIntEnergies causes failures in the zeroD module, albeit only on windows and sundials runners.

Checklist

• The pull request includes a clear description of this code change
• Commit messages have short titles and reference relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• Style & formatting of contributed code follows contributing guidelines
• The pull request is ready for review

[codecov]

Codecov Report

Attention: Patch coverage is 69.09091% with 17 lines in your changes missing coverage. Please review.

Project coverage is 74.39%. Comparing base (2e0d8ac) to head (3e3b709).

Files with missing lines	Patch %	Lines
include/cantera/thermo/ThermoPhase.h	61.36%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1837      +/-   ##
==========================================
- Coverage   74.41%   74.39%   -0.02%     
==========================================
  Files         382      382              
  Lines       53411    53328      -83     
  Branches     9026     9020       -6     
==========================================
- Hits        39747    39676      -71     
+ Misses      10617    10606      -11     
+ Partials     3047     3046       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.