Adding Enthalpy Equation for LinearFV

[freiler]

Motivation

To solve temperature-dependent thermophysical properties, specially when specific heat is a function of temperature.
In addition, the enthalpy formulation for the energy conservation equation is useful for phase change and combustion.

Design

Design includes the necessary classes and methods to solve the enthalpy equation conservation in LinearFV, including but not limited to:

• LinearFVEnthalpyFunctorMaterial to handle the conversion between temperature and enthalpy in both ways for fields and boundary conditions.
• Boundary conditions conversion to handle heat flux and fixed temperature bcs.
• Declaration of temperature aux variable under the hood

Impact

It will add something new and not modify existing APIs.