and changed to be an energy implicit correction to a temperature gradient
based heat-flux. This formulation is both energy conservative and temperature
consistent.
The wallHeatFlux functionObject has been updated to use a consistent heat-flux
from the heSolidThermo.
so that foamDictionary conveniently supports the same format as the #includeFunc
argument list, e.g.
foamDictionary -set 'fieldAverage(U, p, prime2Mean = yes)' fieldAverage
The unnamed field arguments 'U' and 'p' are ignored by foamDictionary.
The vtk libraries are not fully independent of the paraview
installation, so in order to have multiple valid compilations of the
PVReaders (which is useful for testing) we need multiple versions of
these libraries, too. So, these libraries have been put into
$PV_PLUGIN_PATH, which is a paraview-version-specific subdirectory of
$FOAM_LIBBIN.
All heat transfers that result from mass-transfer are now implemented in
terms of sensible enthalpy, so that they are consistent regardless of
which form of energy is being solved for. This has removed some spurious
temperature anomalies from a number of cases involving mass-transfer.
All heat transfers that result from mass-transfer are now linearised. In
the case of multi-specie systems this requires the specification of a
residual mass fraction, which is given by a new "residualY" keyword in
the constant/phaseProperties dictionary. If this entry is omitted for
multi-specie systems then linearisation is deactivated.
**** Details for developers ****
Methods have been added to the base heat transfer phase systems to
permit energy transfer as a result of phase change, without coupling to
a diffusive heat transfer model. These functions require a "weight" to
be specified in the call to define how the latent heat is divided
between either side of the interface. A weight of 0 indicates that the
latent heat is dissipated entirely in the upwind phase, and 1 means it
is entirely in the downwind phase.
The forms of latent heat calculation and transfer have been standardised
between the various phase systems. There are now two methods of
calculating the latent heat, and two methods of applying the transfer
(see below for details). These options are currently hard-coded into the
systems that use them, but they could be made user modifiable
per-mass-transfer in future.
Interface temperatures are now stored by the derived phase systems
alongside their corresponding mass transfer rates. These temperatures
are passed by argument to the phase-change heat transfer methods
provided by the base heat transfer systems. This allows multiple
mechanisms of mass transfer each involving different interface state to
occur across the same interface.
These changes have allowed all phase systems to use the same set of
base energy-transfer functionality.
**** Even more details for developers ****
The two forms of latent heat scheme available are:
symmetric: The latent heat is calculated as the difference between
the interface enthalpies on either side of an interface.
This is the simplest form.
upwind: The latent heat is calculated as the difference between
the bulk enthalpy on the side of the interface that mass
is being transferred from and the interface enthalpy on
the side of the interface that mass is transferring to.
This form may confer some stability benefits.
The two format of latent heat transfer are:
heat: The latent heat is applied by transferring heat unequally
on either side of an interface using the difference
between the bulk phase temperatures and the interface
temperature. No explicit latent heat source is required.
This method has a stability advantage over the "mass"
option, but the transfer is not energy conservative
unless the interface temperature is exactly correct.
mass: The latent heat is applied as an explicit mass transfer
source to both sides of an interface. The ratio between
the heat transfer coefficients on either side determines
what proportion of the latent heat source ends up in each
phase. Heat transfer is calculated equally on both sides
of an interface using bulk phase temperatures and is not
coupled to the thermal effect of phase change. This
method has the advantage of being energy conservative
even if the interface temperature is not exact, but it is
less stable than the "heat" option at extreme conditions.
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.
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.
