The handling of species transfer within the interface-composition phase
change system has been sigificantly altered. The explicit-implicit
caching of the mass transfer has been removed and been replaced with
storage of an Su-Sp coefficient pair. The mass transfer is now generated
on the fly from these coefficients.
These fixes resolve a number of issues involving multiple species for
which the pimple loop did not converge to a conservative solution. It
also removes the requirement for a second evaluation of the mass
transfer after solution of the species fraction equations.
This work was supported by Zhen Li, at Evonik
This fixes a consistency issue in the interface-composition method, and
also seems to improve stability/convergence of the pimple iteration in
the presence of significant mass transfer.
Now lnInclude are created as required by the presence of entries in the EXE_INC
variable in the Make/options file. This removes the need for calling
wmakeLnInclude in various Allwmake files to ensure the existence of the
lnInclude directories prior to compilation of dependent libraries.
Added a function object for the reacting Euler-Euler solvers which
evaluates and writes out the blended interfacial forces acting on a
given phase (drag, virtual mass, lift, wall lubrication and turbulent
dispersion).
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum
Dresden - Rossendorf (HZDR)
The Sauter mean diameter calculation has been modified to be more stable
in the limit of vanishing phase fraction. The calculation of the overall
Sauter mean diameter for a populationBalance involving more than one
velocityGroup has been removed. This calculation depends upon the phase
fraction and it is not stable as the fractions tend to zero. The overall
Sauter mean diameter is only used for post-processing and can still be
recovered from the individual diameter fields of the involved
velocityGroups.
Some parts of the population balance modeling have also been renamed and
refactored.
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum
Dresden - Rossendorf (HZDR)
The calculations for mixture rho and U have been changed so that they
represent phase-averaged quantities over the moving phases only.
The mixture density is used as part of the pressure solution to
calculate buoyancy forces. The pressure within a stationary phase is
considered to be decoupled from the moving phases; i.e., it is
considered self-supporting. Therefore the stationary phase density
should not form a part of buoyancy calculations. This change to the
definition of mixture density ensures this.
Lookup of models associated with unordered phase pairs now searches for
both possible pair names; e.g. gasAndLiquid and liquidAndGas.
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum
Dresden - Rossendorf (HZDR)
The nonRandomTwoLiquid and Roult interface composition models have been
instantiated (and updated so that they compile), and a fuller set of
multi-component liquids and multi-component and reacting gases have been
used.
The selection name of the saturated and nonRandomTwoLiquid models have
also been changed to remove the capitalisation from the first letter, as
is consistent with other sub-models that are not proper nouns.
This model transfers a dispersed droplet phase to a film phase at a rate
relative to its intersection with a third phase. The third phase is
termed the "surface". It can be enabled in constant/phaseProperties as
follows:
phaseTransfer
(
(droplets and film)
{
type deposition;
droplet droplets;
surface solid;
efficiency 0.1;
}
);
The efficiency is an empirical factor which represents a reduction in
collisions as a result of droplets flowing around the surface phase and
not coalescing on impact.
This work was supported by Georg Skillas and Zhen Li, at Evonik
An additional layer has been added into the phase system hierarchy which
facilitates the application of phase transfer modelling. These are
models which exchange mass between phases without the thermal coupling
that would be required to represent phase change. They can be thought of
as representation changes; e.g., between two phases representing
different droplet sizes of the same physical fluid.
To facilitate this, the heat transfer phase systems have been modified
and renamed and now both support mass transfer. The two sided version
is only required for derivations which support phase change.
The following changes to case settings have been made:
- The simplest instantiated phase systems have been renamed to
basicTwoPhaseSystem and basicMultiphaseSystem. The
heatAndMomentumTransfer*System entries in constant/phaseProperties files
will need updating accordingly.
- A phaseTransfer sub-model entry will be required in the
constant/phaseProperties file. This can be an empty list.
- The massTransfer switch in thermal phase change cases has been renamed
phaseTransfer, so as not to be confused with the mass transfer models
used by interface composition cases.
This work was supported by Georg Skillas and Zhen Li, at Evonik
Blended models are now registered and can be looked up in the same way
as regular interfacial models via the phaseSystem::lookupSubModel
method. For example, to access the blended drag model, the following
code could be used:
const BlendedInterfacialModel<dragModel>& drag =
fluid.lookupSubModel<BlendedInterfacialModel<dragModel>>
(
phasePair(gas, liquid)
);
Here, "fluid" is the phase system, and "gas" and "liquid" are the phase
models between which the blended drag model applies.
Also added tutorial case demonstrating usage. Note that the new drag
models are symmetric and should be used without any blending.
This work was supported by Georg Skillas and Zhen Li, at Evonik
