renaming the legacy keywords
RASModel -> model
LESModel -> model
laminarModel -> model
which is simpler and clear within the context in which they are specified, e.g.
RAS
{
model kOmegaSST;
turbulence on;
printCoeffs on;
}
rather than
RAS
{
RASModel kOmegaSST;
turbulence on;
printCoeffs on;
}
The old keywords are supported for backward compatibility.
This part of the name is unnecessary, as it is clear from context that
the name refers to a reaction. The selector has been made backwards
compatible so that old names will still read successfuly.
Reaction names are now consistently camel-cased for readability. Most
names have not been affected because the reaction rate name is a proper
noun and is therefore already capitalised (e.g., Arrhenius, Janev,
Landau, etc ...). Reactions that have been affected are as follows.
Old name New name
irreversibleinfiniteReaction irreversibleInfiniteReaction
irreversiblepowerSeriesReaction irreversiblePowerSeriesReaction
irreversiblethirdBodyArrheniusReaction irreversibleThirdBodyArrheniusReaction
nonEquilibriumReversibleinfiniteReaction nonEquilibriumReversibleInfiniteReaction
nonEquilibriumReversiblethirdBodyArrheniusReaction nonEquilibriumReversibleThirdBodyArrheniusReaction
reversibleinfiniteReaction reversibleInfiniteReaction
reversiblepowerSeriesReaction reversiblePowerSeriesReaction
reversiblethirdBodyArrheniusReaction reversibleThirdBodyArrheniusReaction
irreversiblefluxLimitedLangmuirHinshelwoodReaction irreversibleFluxLimitedLangmuirHinshelwoodReaction
irreversiblesurfaceArrheniusReaction irreversibleSurfaceArrheniusReaction
reversiblesurfaceArrheniusReaction reversibleSurfaceArrheniusReaction
solidChemistryModel is not implemented in a general way but specialised to form
the basis of the highly specific pyrolysis mode. The handling of reactions is
hard-coded for forward reactions only, the Jacobian was present but incomplete
so any ODE solvers requiring the Jacobian would either fail, diverge or produce
incorrect results. It is not clear if many or any parts of the
solidChemistryModel are correct, in particular there is no handling for the
solid surface area per unit volume. After a lot of refactoring work it has
become clear that solidChemistryModel needs a complete rewrite and can benefit
from all the recent development work done on the now more general
StandardChemistryModel.
kappa is now obtained from the fluidThermo for laminar regions, the turbulence
model for turbulent regions and the solidThermo for solid regions. The "lookup"
option previously supported allowed for energy-temperature inconsistent and
incorrect specification of kappa and was not used. Without this incorrect
option there is now no need to specify a kappaMethod thus significantly
simplifying the use boundary conditions derived from temperatureCoupledBase.
Now that the reaction system is separated from the mixture thermodynamics it is
possible to rationalise singleStepCombustion so that it instantiates a single
reaction as it should. This simplifies the code, maintenance and the user
interface not that the combustionProperties file contains a single reaction
rather than a list.
This allows much greater flexibility in the instantiation of reaction system
which may in general depend on fields other than the thermodynamic state. This
also simplifies mixture thermodynamics removing the need for the reactingMixture
and the instantiation of all the thermodynamic package combinations depending on
it.
which are now read directly from the thermophysicalProperties dictionary for
consistency with non-reacting mixture thermodynamics. The species thermo and
reactions lists can still be in separate files if convenient and included into
the thermophysicalProperties file using the standard dictionary #include.
This formalises the flexible and extensible OpenFOAM thermodynamics and reaction
format as the direct input to OpenFOAM solvers. The CHEMKIN format is still
supported by first converting to the OpenFOAM format using the chemkinToFoam
utility.
The radiation modelling library has been moved out of
thermophysicalProperties into the top-level source directory. Radiation
is a process, not a property, and belongs alongside turbulence,
combustion, etc...
The namespaces used within the radiation library have been made
consistent with the rest of the code. Selectable sub-models are in
namespaces named after their base classes. Some models have been
renamed remove the base type from the suffix, as this is unnecessary.
These renames are:
Old name: New name:
binaryAbsorptionEmission binary
cloudAbsorptionEmission cloud
constantAbsorptionEmission constant
greyMeanAbsorptionEmission greyMean/greyMeanCombustion
greyMeanSolidAbsorptionEmission greyMeanSolid
wideBandAbsorptionEmission wideBand/wideBandCombustion
cloudScatter cloud
constantScatter constant
mixtureFractionSoot mixtureFraction
Some absorption-emission models have been split into versions which do
and don't use the heat release rate. The version that does has been
given the post-fix "Combustion" and has been moved into the
combustionModels library. This removes the dependence on a registered
Qdot field, and makes the models compatible with the recent removal of
that field from the combustion solvers.
This allows coefficients of the constantAbsorptionEmission and
constantScatter to be entered as pure numbers, with the name and
dimensions set automatically, rather than having to specify them
manually.
Added headers to all reactions files to prevent warnings in paraview.
Added references for known mechanisms. Removed unused reaction and
thermophysical property files.
Now for transient simulations "Final" solver settings are required for ALL
equations providing consistency between the solution of velocity, energy,
composition and radiation properties.
However "Final" relaxation factors are no longer required for fields or
equations and if not present the standard value for the variable will be
applied. Given that relaxation factors other than 1 are rarely required for
transient runs and hence the same for all iterations including the final one
this approach provide simpler input while still providing the flexibility to
specify a different value for the final iteration if required. For steady cases
it is usual to execute just 1 outer iteration per time-step for which the
standard relaxation factors are appropriate, and if more than one iteration is
executed it is common to use the same factors for both. In the unlikely event
of requiring different relaxation factors for the final iteration this is still
possible to specify via the now optional "Final" specification.
including third-body and pressure dependent derivatives, and derivative of the
temperature term. The complete Jacobian is more robust than the incomplete and
partially approximate form used previously and improves the efficiency of the
stiff ODE solvers which rely on the Jacobian.
Reaction rate evaluation moved from the chemistryModel to specie library to
simplfy support for alternative reaction rate expressions and associated
Jacobian terms.
Temperature clipping included in the Reaction class. This is inactive by default
but for most cases it is advised to provide temperature limits (high and
low). These are provided in the foamChemistryFile with the keywords Thigh and
Tlow. When using chemkinToFoam these values are set to the limits of the Janaf
thermodynamic data. With the new Jacobian this temperature clipping has proved
very beneficial for stability and for some cases essential.
Improvement of the TDAC MRU list better integrated in add and grow functions.
To get the most out of this significant development it is important to re-tune
the ODE integration tolerances, in particular the absTol in the odeCoeffs
sub-dictionary of the chemistryProperties dictionary:
odeCoeffs
{
solver seulex;
absTol 1e-12;
relTol 0.01;
}
Typically absTol can now be set to 1e-8 and relTol to 0.1 except for ignition
time problems, and with theses settings the integration is still robust but for
many cases a lot faster than previously.
Code development and integration undertaken by
Francesco Contino
Henry G. Weller, CFD Direct
runApplication isn't needed for foamDictionary as it doesn't log
anything of consequence. Using runApplication leads to false unconfirmed
completion warnings in the test loop as foamDictionary does not generate
an end statement.
Now if a <field> file does not exist first the compressed <field>.gz file is
searched for and if that also does not exist the <field>.orig file is searched
for.
This simplifies case setup and run scripts as now setField for example can read
the <field>.orig file directly and generate the <field> file from it which is
then read by the solver. Additionally the cleanCase function used by
foamCleanCase and the Allclean scripts automatically removed <field> files if
there is a corresponding <field>.orig file. So now there is no need for the
Allrun scripts to copy <field>.orig files into <field> or for the Allclean
scripts to explicitly remove them.
The new optional switch 'writeCyclicMatch' can be set to 'true' to enable the writing of
the cyclic match OBJ files; defaults to 'false'.
Patch contributed by Bruno Santos
Resolves patch request https://bugs.openfoam.org/view.php?id=2685
The standard naming convention for heat flux is "q" and this is used for the
conductive and convective heat fluxes is OpenFOAM. The use of "Qr" for
radiative heat flux is an anomaly which causes confusion, particularly for
boundary conditions in which "Q" is used to denote power in Watts. The name of
the radiative heat flux has now been corrected to "qr" and all models, boundary
conditions and tutorials updated.
The defaultCoeffs entry is now redundant and supported only for backward
compatibility. To specify a liquid with default coefficients simply leave the
coefficients dictionary empty:
liquids
{
H2O {}
}
Any or all of the coefficients may be overridden by specifying the properties in
the coefficients dictionary, e.g.
liquids
{
H2O
{
rho
{
a 1000;
b 0;
c 0;
d 0;
}
}
}
The fundamental properties provided by the specie class hierarchy were
mole-based, i.e. provide the properties per mole whereas the fundamental
properties provided by the liquidProperties and solidProperties classes are
mass-based, i.e. per unit mass. This inconsistency made it impossible to
instantiate the thermodynamics packages (rhoThermo, psiThermo) used by the FV
transport solvers on liquidProperties. In order to combine VoF with film and/or
Lagrangian models it is essential that the physical propertied of the three
representations of the liquid are consistent which means that it is necessary to
instantiate the thermodynamics packages on liquidProperties. This requires
either liquidProperties to be rewritten mole-based or the specie classes to be
rewritten mass-based. Given that most of OpenFOAM solvers operate
mass-based (solve for mass-fractions and provide mass-fractions to sub-models it
is more consistent and efficient if the low-level thermodynamics is also
mass-based.
This commit includes all of the changes necessary for all of the thermodynamics
in OpenFOAM to operate mass-based and supports the instantiation of
thermodynamics packages on liquidProperties.
Note that most users, developers and contributors to OpenFOAM will not notice
any difference in the operation of the code except that the confusing
nMoles 1;
entries in the thermophysicalProperties files are no longer needed or used and
have been removed in this commet. The only substantial change to the internals
is that species thermodynamics are now "mixed" with mass rather than mole
fractions. This is more convenient except for defining reaction equilibrium
thermodynamics for which the molar rather than mass composition is usually know.
The consequence of this can be seen in the adiabaticFlameT, equilibriumCO and
equilibriumFlameT utilities in which the species thermodynamics are
pre-multiplied by their molecular mass to effectively convert them to mole-basis
to simplify the definition of the reaction equilibrium thermodynamics, e.g. in
equilibriumCO
// Reactants (mole-based)
thermo FUEL(thermoData.subDict(fuelName)); FUEL *= FUEL.W();
// Oxidant (mole-based)
thermo O2(thermoData.subDict("O2")); O2 *= O2.W();
thermo N2(thermoData.subDict("N2")); N2 *= N2.W();
// Intermediates (mole-based)
thermo H2(thermoData.subDict("H2")); H2 *= H2.W();
// Products (mole-based)
thermo CO2(thermoData.subDict("CO2")); CO2 *= CO2.W();
thermo H2O(thermoData.subDict("H2O")); H2O *= H2O.W();
thermo CO(thermoData.subDict("CO")); CO *= CO.W();
// Product dissociation reactions
thermo CO2BreakUp
(
CO2 == CO + 0.5*O2
);
thermo H2OBreakUp
(
H2O == H2 + 0.5*O2
);
Please report any problems with this substantial but necessary rewrite of the
thermodynamic at https://bugs.openfoam.org
Henry G. Weller
CFD Direct Ltd.
