and renamed defaultSpecie as its mass fraction is derived from the sum of the
mass fractions of all other species and it need not be inert but must be present
everywhere, e.g. N2 in air/fuel combustion which can be involved in the
production of NOx.
The previous name inertSpecie in thermophysicalProperties is supported for
backward compatibility.
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.
Fourier, eddyDiffusivity and nonUnityLewisEddyDiffusivity thermophysical
transport models now apply an implicit energy correction to a temperature
gradient based heat-flux to provide computational stability and efficiency while
converging to temperature gradient based solution. This ensures consistent heat
exchange between fluid and solid regions in CHT cases and with heat-flux
boundaries.
The Fourier and eddyDiffusivity models support single specie systems only
whereas nonUnityLewisEddyDiffusivity supports specie diffusion with independent
specification of turbulent Prandtl and Schmidt numbers, i.e. non-unity Lewis
number.
The unityLewisFourier and unityLewisEddyDiffusivity thermophysical transport
models use an implicit energy gradient based heat-flux which is optimal for
numerical stability and convergence but does not guarantee consistent heat
exchange between fluid and solid regions and heat-flux boundaries in the
presence of gradients of heat capacity. Both of these models support specie
diffusion with the restriction that the laminar and turbulent Prandtl and
Schmidt numbers are equal, i.e. unity Lewis number.
The thermophysical transport model is specified in the optional
thermophysicalTransport dictionary; if this file is not present the
unityLewisFourier model is selected for laminar and unityLewisEddyDiffusivity
for turbulent cases for backward compatibility.
The chtMultiRegionFoam tutorial cases have been updated to use the most
appropriate of the new thermophysical transport models.
Solid thermo no longer requires a pressure field, so solid regions of
chtMultiRegionFoam cases no longer need a 0/<solidRegionName>/p file.
In order for solidThermo to continue to use heThermo and the low level
thermo classes, it now constructs a uniformGeometricScalarField for the
pressure with the value NaN. This is passed into the low-level thermo
models by heThermo. The enforces the requirement that low-level thermo
models used by solidThermo should have no pressure dependence. If an
instantiation is made with pressure dependence, the code will fail with
a floating point error.
Most fvOptions change the state of the fields and equations they are applied to
but do not change internal state so it makes more sense that the interface is
const, consistent with MeshObjects. For the few fvOptions which do maintain a
changing state the member data is now mutable.
This is useful for testing purposes in comparison with rhoPimpleFoam.
Also made a fix to the handling of multivariate convection schemes in
chtMultiRegionFoam.
foamDictionary executions are now wrapped by runApplication like any
other execution so that they do not print during a test loop.
foamDictionary does not produce a conforming log, however, so
log.foamDictionary has been filtered out of the formation of the test
loop report so that false failures are not reported.
The new optional 'slash' scoping syntax is now the default and provides a more
intuitive and flexible syntax than the previous 'dot' syntax, corresponding to
the common directory/file access syntax used in UNIX, providing support for
reading entries from other dictionary files.
In the 'slash' syntax
'/' is the scope operator
'../' is the parent dictionary scope operator
'!' is the top-level dictionary scope operator
Examples:
internalField 3.4;
active
{
type fixedValue;
value.air $internalField;
}
inactive
{
type anotherFixedValue;
value $../active/value.air;
anotherValue $!active/value.air;
sub
{
value $../../active/value.air;
anotherValue $!active/value.air;
}
}
"U.*"
{
solver GAMG;
}
e.air
{
$U.air;
}
external
{
value $testSlashDict2!active/value.air;
}
active2
{
$testSlashDict2!active;
}
If there is a part of the keyword before the '!' then this is taken to be the
file name of the dictionary from which the entry will be looked-up using the
part of the keyword after the '!'. For example given a file testSlashDict containing
internalField 5.6;
active
{
type fixedValue;
value.air $internalField;
}
entries from it can be read directly from another file, e.g.
external
{
value $testSlashDict2!active/value.air;
}
active2
{
$testSlashDict2!active;
}
which expands to
external
{
value 5.6;
}
active2
{
type fixedValue;
value.air 5.6;
}
These examples are provided in applications/test/dictionary.
The the default syntax can be changed from 'slash' to 'dot' in etc/controlDict
to revert to the previous behaviour:
OptimisationSwitches
{
.
.
.
// Default dictionary scoping syntax
inputSyntax slash; // Change to dot for previous behaviour
}
or within a specific dictionary by adding the entry
See applications/test/dictionary/testDotDict.
Added optional pressure reference pRef to p_rgh in buoyantPimpleFoam,
buoyantSimpleFoam and chtMultiRegionFoam which handles cases in which the
pressure variation is small compared to the pressure level more accurately.
The pRef value is provided in the optional constant/pRef file.
All tutorials and templates have been updated to use pRef as appropriate.
Only perfectGas and real-gas equations of state are consistent with standard
Janaf thermo data based on Cp. Using other equations of state is possible but
the Janaf Cp data would have to be modified for consistency.
The solid is currently assumed incompressible (the solid pressure is not
updated) and in general would be near incompressible so internal energy is a
more appropriate energy choice than enthalpy which would require a pressure work
term currently not implemented. Additionally due to the way in which the
conduction is handled in terms of the gradient of energy the accuracy of the
current enthalpy implementation is sensitive to the pressure distribution as
this introduces an enthalpy gradient from the p/rho term which would need to be
corrected; this issue is avoided by solving for internal energy instead.
This improvement requires the scheme and solver settings for the solids in
chtMultiRegionFoam cases to be changed from "h" to "e" and the thermo-physical
properties in <solid>/thermophysicalProperties to be set to the corresponding
internal energy forms, e.g.:
thermo eConst;
.
.
.
energy sensibleInternalEnergy;
All tutorials have be updated to reflect this and provide guidance when updating
cases.
providing the shear-stress term in the momentum equation for incompressible and
compressible Newtonian, non-Newtonian and visco-elastic laminar flow as well as
Reynolds averaged and large-eddy simulation of turbulent flow.
The general deviatoric shear-stress term provided by the MomentumTransportModels
library is named divDevTau for compressible flow and divDevSigma (sigma =
tau/rho) for incompressible flow, the spherical part of the shear-stress is
assumed to be either included in the pressure or handled separately. The
corresponding stress function sigma is also provided which in the case of
Reynolds stress closure returns the effective Reynolds stress (including the
laminar contribution) or for other Reynolds averaged or large-eddy turbulence
closures returns the modelled Reynolds stress or sub-grid stress respectively.
For visco-elastic flow the sigma function returns the effective total stress
including the visco-elastic and Newtonian contributions.
For thermal flow the heat-flux generated by thermal diffusion is now handled by
the separate ThermophysicalTransportModels library allowing independent run-time
selection of the heat-flux model.
During the development of the MomentumTransportModels library significant effort
has been put into rationalising the components and supporting libraries,
removing redundant code, updating names to provide a more logical, consistent
and extensible interface and aid further development and maintenance. All
solvers and tutorials have been updated correspondingly and backward
compatibility of the input dictionaries provided.
Henry G. Weller
CFD Direct Ltd.
Following the generalisation of the TurbulenceModels library to support
non-Newtonian laminar flow including visco-elasticity and extensible to other
form of non-Newtonian behaviour the name TurbulenceModels is misleading and does
not properly represent how general the OpenFOAM solvers now are. The
TurbulenceModels now provides an interface to momentum transport modelling in
general and the plan is to rename it MomentumTransportModels and in preparation
for this the turbulenceProperties dictionary has been renamed momentumTransport
to properly reflect its new more general purpose.
The old turbulenceProperties name is supported for backward-compatibility.
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 significant improvement is flexibility of SemiImplicitSource required a
generalisation of the source specification syntax and all tutorials have been
updated accordingly.
Description
Semi-implicit source, described using an input dictionary. The injection
rate coefficients are specified as pairs of Su-Sp coefficients, i.e.
\f[
S(x) = S_u + S_p x
\f]
where
\vartable
S(x) | net source for field 'x'
S_u | explicit source contribution
S_p | linearised implicit contribution
\endvartable
Example tabulated heat source specification for internal energy:
\verbatim
volumeMode absolute; // specific
sources
{
e
{
explicit table ((0 0) (1.5 $power));
implicit 0;
}
}
\endverbatim
Example coded heat source specification for enthalpy:
\verbatim
volumeMode absolute; // specific
sources
{
h
{
explicit
{
type coded;
name heatInjection;
code
#{
// Power amplitude
const scalar powerAmplitude = 1000;
// x is the current time
return mag(powerAmplitude*sin(x));
#};
}
implicit 0;
}
}
\endverbatim
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.
Description
Calculates the thermal comfort quantities predicted mean vote (PMV) and
predicted percentage of dissatisfaction (PPD) based on DIN ISO EN 7730:2005.
Usage
\table
Property | Description | Required | Default value
clothing | The insulation value of the cloth | no | 0
metabolicRate | The metabolic rate | no | 0.8
extWork | The external work | no | 0
Trad | Radiation temperature | no | -1
relHumidity | Relative humidity of the air | no | 50
pSat | Saturation pressure of water | no | -1
tolerance | Residual control for the cloth temperature | no | 1e-5
maxClothIter | Maximum number of iterations | no | 0
meanVelocity | Use a constant mean velocity in the whole domain | no |\
false
\endtable
\table
Predicted Mean Vote (PMV) | evaluation
+ 3 | hot
+ 2 | warm
+ 1 | slightly warm
+ 0 | neutral
- 1 | slightly cool
- 2 | cool
- 3 | cold
\endtable
\verbatim
comfortAnalysis
{
type comfort;
libs ("libfieldFunctionObjects.so");
executeControl writeTime;
writeControl writeTime;
}
\endverbatim
The new tutorial case heatTransfer/buoyantSimpleFoam/comfortHotRoom is provided
to demonstrate the calculation of PMV and PPD using the comfort functionObject.
This work is based on code and case contributed by Tobias Holzmann.
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.
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.
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.
With the selection of the Boussinesq equation of state the general buoyancy
solvers buoyantSimpleFoam and buoyantPimpleFoam can be used instead of the
specialised Boussinesq solvers avoiding the need for special implementation of
thermal and pressure boundary conditions and providing support for radiation and
fvOptions which would not have been feasible or practical in the Boussinesq
solvers.
Other incompressible equations of state are also supported; for most gaseous
problems the incompressiblePerfectGas equation of state is likely to be more
accurate than the Boussinesq equation of state.
The buoyantBoussinesq[SP]impleFoam tutorials have been updated and moved to the
corresponding buoyant[SP]impleFoam directories.
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 tutorial serves as a reference of how to create a multi-region
mesh with layer addition.
The multiRegionHeater tutorial and it's variants have been removed as
the geometry is not meaningful and the functionality is now all
represented elsewhere.
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.
This function object writes out the heat release rate field for a
combustion model. This is useful for solvers where combustion is
optional, and which do not therefore write out the heat release rate by
default; e.g., chtMultiRegionFoam and reactingTwoPhaseEulerFoam.
The tutorial has been converted from two-dimensions to a wedge and the
flow has been swirl stabilised. The turbulence parameters have been made
physical. The transport schemes have been increased to second order. The
reaction mechanism has been changed to one from a publically accessible
reference. The gas thermodynamics have been made incompressible, and the
pressure offset around zero, which improves the behaviour of the
pressure solution.
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.
to avoid the need to evaluate departure functions and simplify evaluation of the
temperature. In general it makes more sense to use and e/Cv based
thermodynamics when solving for internal energy rather than h/Cp and have
convert between the energy forms.
All related tutorials and test cases have also been updated.
Changed liquid thermo from sensibleEnthalpy to sensibleInternalEnergy in
tutorials. It is generally more convergent and stable to solve for internal
energy if the fluid is incompressible or weakly compressible.
