Expanded the documentation and updated the mean free path calculation
Patch contributed by Institute of Fluid Dynamics,
Helmholtz-Zentrum Dresden - Rossendorf (HZDR)
alphah is derived from kappa/Cp and mixing rules should be applied to kappa and
Cp separately rather than to alphah so it is more consistent to calculate the
mixture alphah from the mixture kappa and Cp at the heThermo level.
This provides support for mixtures of species in which coefficient mixing of the
thermophysical properties is not possible/practical, e.g. tabulated data.
Thermodynamic properties are mass-fraction mixed and transport properties
mole-fraction mixed.
In the new general mixture framework it is now possible to implement more
complex mixing rules which is particularly useful for transport properties,
e.g. the Wilke model for gases. Combinations of coefficient mixing for thermo
and complex mixing for transport is also supported.
valueMultiComponentMixture is currently instantiated on all the standard
tabulated thermo combination:
thermoType
{
type heRhoThermo;
mixture valueMultiComponentMixture;
transport tabulated;
thermo hTabulated;
energy sensibleEnthalpy;
equationOfState icoTabulated;
specie specie;
}
but can be used for any of the current or future combinations.
Optional switches "splitPhaseFlux" and "meanFluxReference" are now provided and
can be set true in fvSolution e.g.
solvers
{
"alpha.*"
{
nAlphaCorr 1;
nAlphaSubCycles 2;
splitPhaseFlux true;
meanFluxReference true;
}
.
.
.
to reinstate the previous form of phase flux limiters in which the mean and
phase flux differences are interpolated separately and the limited correction
referenced to the mean rather than phase flux. This form of discretisation and
limiting is more aggressive than the latest version and hence less accurate but
it is hoped that the latest form of limitSum will handle the boundedness at the
upper limit reliably allowing the new more accurate limiters to be used for most
if not all multiphase simulations.
limitSum operates on the sum positive and negative flux corrections as it did
originally to guarantee that the phase fractions sum to 1 but now on the scaled
moving sub-set of the phases so that it handles the presence of stationary
phases in a consistent manner.
Additionally limitSum is now applied to two-phase systems even when only one of
the phases is solved for to ensure the solution is the same irrespective of
which phase fraction is solved or if both are solved.
compressibleMultiphaseInterFoam and multiphaseInterFoam have been updated to use
the same form of limitSum as multiphaseInterFoam but this does not change their
behaviour, it is to reduce code duplication.
psiReactionThermo- and rhoReactionThermo-s now derive from an additional
fluidReactionThermo class and are included on a corresponding run-time
selection table.
This means all multi-specie solvers can now be used with either
compressibility/psi- or density/rho-based thermodynamic models, in the
same way that non-reacting solvers can.
rhoReactingFoam has been removed, as it is no longer necessary now that
reactingFoam can operate with density-based thermodynamics.
rhoReactingBuoyantFoam has also been renamed buoyantReactingFoam to
reflect the fact that it is no longer a variant specific to
density-based thermodynamics; it can now operate with
compressibility-based thermodynamic models as well.
The change is fully backwards compatible. All cases should continue to
run without modification, apart from the fact that a different solver
might need to be called.
