- makes for clearer code

ENH: make writeIfDifferent part of Ostream

Patch contributed by Juho Peltola, VTT.

Resolves patch request https://bugs.openfoam.org/view.php?id=2521

Patch contributed by Juho Peltola, VTT
Resolves patch request https://bugs.openfoam.org/view.php?id=2446

to handle the effect of condensation and evaporation on bubble size

to handle the size of bubbles created by boiling.  To be used in
conjunction with the alphatWallBoilingWallFunction boundary condition.

The IATE variant of the wallBoiling tutorial case is provided to
demonstrate the functionality:

tutorials/multiphase/reactingTwoPhaseEulerFoam/RAS/wallBoilingIATE

Patch contributed by Juho Peltola

Contributed by Juho Peltola, VTT

Notable changes:

    1. The same wall function is now used for both phases, but user must
       specify phaseType ‘liquid’ or ‘vapor’

    2. Runtime selectable submodels for:
       - wall heat flux partitioning between the phases
       - nucleation site density
       - bubble departure frequency
       - bubble departure diameter

    3. An additional iteration loop for the wall boiling model in case
       the initial guess for the wall temperature proves to be poor.

The wallBoiling tutorial has been updated to demonstrate this new functionality.

GeometricField: Renamed internalField() -> primitiveField() and dimensionedInternalField() -> internalField()

These new names are more consistent and logical because:

primitiveField():
primitiveFieldRef():
    Provides low-level access to the Field<Type> (primitive field)
    without dimension or mesh-consistency checking.  This should only be
    used in the low-level functions where dimensional consistency is
    ensured by careful programming and computational efficiency is
    paramount.

internalField():
internalFieldRef():
    Provides access to the DimensionedField<Type, GeoMesh> of values on
    the internal mesh-type for which the GeometricField is defined and
    supports dimension and checking and mesh-consistency checking.

The deprecated non-const tmp functionality is now on the compiler switch
NON_CONST_TMP which can be enabled by adding -DNON_CONST_TMP to EXE_INC
in the Make/options file.  However, it is recommended to upgrade all
code to the new safer tmp by using the '.ref()' member function rather
than the non-const '()' dereference operator when non-const access to
the temporary object is required.

Please report any problems on Mantis.

Henry G. Weller
CFD Direct.

Code and tutorial case provided by Juho Peltola