Description
Calculates the natural logarithm of the specified scalar field.
Performs \f$ln(max(x, a))\f$ where \f$x\f$ is the field and \f$a\f$ an
optional clip to handle 0 or negative \f$x\f$. Dimension checking can
optionally be suspended for this operation if \f$x\f$ is dimensioned.
Example of function object specification:
\verbatim
log1
{
type log;
libs ("libfieldFunctionObjects.so");
field p;
clip 1e-3;
checkDimensions no;
}
\endverbatim
or using \c postProcess
\verbatim
postProcess -func 'log(p, clip=1e-3, checkDimensions=no)'
\endverbatim
Usage
\table
Property | Description | Required | Default value
type | Type name: log | yes |
clip | Clip value | no |
checkDimensions | Dimension checking switch | no |
\endtable
Interface composition models are now specified in
constant/phaseProperties like so:
interfaceComposition.gas
(
(gas and water)
{
// ...
}
(gas and oil)
{
// ...
}
);
interfaceComposition.water
(
(water and gas)
{
// ...
}
// ...
);
// ...
I.e., the models associated with diffusive transfer within a phase
"<phase>" are specified in the list "interfaceComposition.<phase>".
Within the list, models are specified in unordered phase pairs
corresponding to the interface.
This replaces a system where models were specified in a single
interfaceComposition list, with the ordered pair entry "(<phase1> in
<phase2>)" meaning transfer within phase1 at the interface with phase2.
This ordered pair syntax is otherwise used for distinguishing between
continuous and dispersed phases. This dual meaning was considered
counter-intuitive. The new entries also more closely resemble the
associated two-resistance heat and mass transfer model specifications.
There are now many types of mass transfer, so massTransfer is now too
generic a term for what these models do. These models generate a
diffusivity which when multiplied by a concentration difference results
in mass transfer, hence the new name.
This change is not backwards compatible. Cases running the interface
composition system will need "massTransfer" entries renamed to
"diffusiveMassTransfer".
Mass transfer for a pair is now no longer available at the top level.
The solver should never need to know mass transfer rates individually;
the dmdts method (which returns all mass transfers simultaneously)
should be sufficient.
In addition the construction of zero-valued fields and addition of
fields into lists and tables within the phase system has been
simplified and code duplication removed.
The density time-derivative terms should always appear in the pressure
equation except when the phase is isochoric (i.e., the equation of state
is constant density) and the phase is pure (as species fraction changes
can also generate changes in density, even for an isochoric equation of
state). The logic in the pressure equations of reactingTwoPhaseEulerFoam
and reactingMultphaseEulerFoam has been changed to fulfil this
requirement.
This has resolved a mass-conservation issue with the
waterAndIsopropanolEvaporation case, which uses a multi-component liquid
with a constant-density equation of state.
A number of fixes have been made to the mass transfer implementations in
the phase system hierarchy in order to improve conservation of energy,
and other properties.
From an implementation perspective, each phase system that defines mass
transfer now has also to implement all property transfers that occur as
a result. The base classes no longer generate the transfers
automatically; it is not in general possible to correctly calculate the
property transfer terms from a single accumulated mass transfer rate.
To facilitate this additional burden on the derived layers, a number of
addDmdt? and addDmidt? methods have been added which compute and add
these transfers into the governing equations in a generic manner. In the
case of simple explicit mass transfers, a mass-transferring system need
only pass a table of the transfer rates to these functions in order to
generate the appropriate transfer terms.
The difference between the addDmdt? and addDmidt? methods is that the
former takes a table of bulk transfers across the interfaces, whilst the
latter takes a table-of-tables of individual species transfers.
Updates to PopulationBalancePhaseSystem and
ThermalPhaseChangePhaseSystem were provided by Timo Niemi, and Juho
Peltola, VTT.
Blended models are now constructed with the same phase order as the
corresponding pair stored by the phase system. This should ultimately
prevent some of the sign comparisons that are currently necessary when
applying models.
//- Switch checking block face orientation
// to ensure that all faces are outward-pointing.
// This check may fail if the block is intentionally very twisted
// for curved edges to be applied and can be switched off.
static Switch checkBlockFaceOrientation;
To switch this check off set
checkBlockFaceOrientation false;
in blockMeshDict.
For reactingTwoPhaseEulerFoam or if only two phases are present in
reactingMultiphaseEulerFoam, new and old formulations are equivalent. In case,
gradients of alpha of more than two phases appear at the same point, it is
necessary to use face based force formulations of turbulent dispersion models,
which take the respective disperse phase fractions into account, and
subsequently blend those.
Patch contributed by Institute of Fluid Dynamics,
Helmholtz-Zentrum Dresden - Rossendorf (HZDR)
Now for the wall in the simpleFoam pitzDaily tutorial case the following
patchField types are printed
group : wall
scalar v2 v2WallFunction
scalar nut nutkWallFunction
scalar k kqRWallFunction
scalar nuTilda zeroGradient
scalar p zeroGradient
scalar omega omegaWallFunction
scalar f fWallFunction
scalar epsilon epsilonWallFunction
vector U noSlip
instead of
group : wall
scalar v2 generic
scalar nut generic
scalar k generic
scalar nuTilda zeroGradient
scalar p zeroGradient
scalar omega generic
scalar f generic
scalar epsilon generic
vector U noSlip
The new optional entry alphap is the as phase fraction below which bubble
generated turbulence is included. The default is 1 for backward compatibility.
The purpose of this limiter is to avoid spurious turbulence generation at and
around the interface where bubbles are not present.
The moving mesh tracking algorithm is deactivated on moving meshes when
the step fraction is 1 and (if the operation requires it) when the
requested tracking fraction is 0. This optimises usage for
post-processing, in which tracking is done at a single point in time at
which the mesh geometry is fixed, rather than over a time-step across
which the mesh moves. It also prevents the need for the storage of
old-time cell centres for such purposes.
Resolves bug report https://bugs.openfoam.org/view.php?id=3343
The recent field-evaluation additions to basicSpecieMixture means that
the interface composition models no longer need knowledge of the
thermodynamic type in order to do efficient evaluation of individual
specie properties, so templating on the thermodynamics is unnecessary.
This greatly simplifies the implementation.
If the functionObject requires an object list rather than a field list the
non-named arguments are now inserted into the object list, for example
functions
{
#includeFunc writeObjects(kEpsilon:G)
}
which is equivalent to
functions
{
#includeFunc writeObjects(objects = (kEpsilon:G))
}
For example the generation term in the k-epsilon turbulence kEpsilon:G is a
temporary field that is specifically named and registered so that it can be
looked-up be the wall-function boundary conditions and requires slightly
different handling compared to normal temporary fields which are not registered.
The tutorials/incompressible/simpleFoam/pitzDaily case now demostrates this
functionality with the addition of
cacheTemporaryObjects
(
kEpsilon:G
);
functions
{
#includeFunc writeObjects(objects = (kEpsilon:G))
}
in controlDict which caches kEpsilon:G and writes it at every write time.
and removed it from equations of state for which it is too inaccurate to be
useful, in particular from perfectFluid which has been superseded by rPolynomial
which is more accurate and naturally support coefficient mixing.
Description
Reciprocal polynomial equation of state for liquids and solids
\f[
1/\rho = C_0 + C_1 T + C_2 T^2 - C_3 p - C_4 p T
\f]
This polynomial for the reciprocal of the density provides a much better fit
than the equivalent polynomial for the density and has the advantage that it
support coefficient mixing to support liquid and solid mixtures in an
efficient manner.
Usage
\table
Property | Description
C | Density polynomial coefficients
\endtable
Example of the specification of the equation of state for pure water:
\verbatim
equationOfState
{
C (0.001278 -2.1055e-06 3.9689e-09 4.3772e-13 -2.0225e-16);
}
\endverbatim
Note: This fit is based on the small amount of data which is freely
available for the range 20-65degC and 1-100bar.
This equation of state is a much better fit for water and other liquids than
perfectFluid and in general polynomials for the reciprocal of the density
converge much faster than polynomials of the density. Currently rPolynomial is
quadratic in the temperature and linear in the pressure which is sufficient for
modest ranges of pressure typically encountered in CFD but could be extended to
higher order in pressure and/temperature if necessary. The other huge advantage
in formulating the equation of state in terms of the reciprocal of the density
is that coefficient mixing is simple.
Given these advantages over the perfectFluid equation of state the libraries and
tutorial cases have all been updated to us rPolynomial rather than perfectFluid
for liquids and water in particular.
