fvcAverage and fvcReconstruct both do divisions or inverses of surface
summed fields. A single-cell zero-dimension case, has no genuine faces
on which to sum, so surface sums are identically zero. This change
detects this situation and returns a zero value instead of failing due
to a divide by zero.
This allows the multiphase test cases to be reduced to just one cell.
to avoid the need for sed'ing the output. This improves performance by avoiding
the need for calling additional commands and generating a temporary file.
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.
Streamlines can now be tracked in both directions from the set of
initial locations. The keyword controlling this behaviour is
"direction", which can be set to "forward", "backward" or "both".
This new keyword superseeds the "trackForward" entry, which has been
retained for backwards compatibility.
For compatibility with all the mesh and related classes in OpenFOAM The 'normal'
function of the 'triangle', 'triFace' and 'face' classes now returns the unit
normal vector rather than the vector area which is now provided by the 'area'
function.
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
Description
This boundary condition extrapolates field to the patch using the near-cell
values and adjusts the distribution to match the specified, optionally
time-varying, mean value. This extrapolated field is applied as a
fixedValue for outflow faces but zeroGradient is applied to inflow faces.
This boundary condition can be applied to pressure when inletOutlet is
applied to the velocity so that a zeroGradient condition is applied to the
pressure at inflow faces where the velocity is specified to avoid an
unphysical over-specification of the set of boundary conditions.
Usage
\table
Property | Description | Required | Default value
meanValue | mean value Function1 | yes |
phi | Flux field name | no | phi
\endtable
Example of the boundary condition specification:
\verbatim
<patchName>
{
type fixedMeanOutletInlet;
meanValue 1.0;
}
\endverbatim
See also
Foam::fixedMeanFvPatchField
Foam::outletInletFvPatchField
Foam::Function1Types
The prghPressureFvPatchScalarField, prghTotalPressureFvPatchScalarField and
prghUniformDensityHydrostaticPressure p_rgh boundary conditions are now derived
from the corresponding pressure boundary conditions using the
PrghPressureFvPatchScalarField template.
