The majority of input parameters now support automatic unit conversion.
Units are specified within square brackets, either before or after the
value. Primitive parameters (e.g., scalars, vectors, tensors, ...),
dimensioned types, fields, Function1-s and Function2-s all support unit
conversion in this way.
Unit conversion occurs on input only. OpenFOAM writes out all fields and
parameters in standard units. It is recommended to use '.orig' files in
the 0 directory to preserve user-readable input if those files are being
modified by pre-processing applications (e.g., setFields).
For example, to specify a volumetric flow rate inlet boundary in litres
per second [l/s], rather than metres-cubed per second [m^3/s], in 0/U:
boundaryField
{
inlet
{
type flowRateInletVelocity;
volumetricFlowRate 0.1 [l/s];
value $internalField;
}
...
}
Or, to specify the pressure field in bar, in 0/p:
internalField uniform 1 [bar];
Or, to convert the parameters of an Arrhenius reaction rate from a
cm-mol-kcal unit system, in constant/chemistryProperties:
reactions
{
methaneReaction
{
type irreversibleArrhenius;
reaction "CH4^0.2 + 2O2^1.3 = CO2 + 2H2O";
A 6.7e12 [(mol/cm^3)^-0.5/s];
beta 0;
Ea 48.4 [kcal/mol];
}
}
Or, to define a time-varying outlet pressure using a CSV file in which
the pressure column is in mega-pascals [MPa], in 0/p:
boundaryField
{
outlet
{
type uniformFixedValue;
value
{
type table;
format csv;
nHeaderLine 1;
units ([s] [MPa]); // <-- new units entry
columns (0 1);
mergeSeparators no;
file "data/pressure.csv";
outOfBounds clamp;
interpolationScheme linear;
}
}
...
}
(Note also that a new 'columns' entry replaces the old 'refColumn' and
'componentColumns'. This is is considered to be more intuitive, and has
a consistent syntax with the new 'units' entry. 'columns' and
'componentColumns' have been retained for backwards compatibility and
will continue to work for the time being.)
Unit definitions can be added in the global or case controlDict files.
See UnitConversions in $WM_PROJECT_DIR/etc/controlDict for examples.
Currently available units include:
Standard: kg m s K kmol A Cd
Derived: Hz N Pa J W g um mm cm km l ml us ms min hr mol
rpm bar atm kPa MPa cal kcal cSt cP % rad rot deg
A user-time unit is also provided if user-time is in operation. This
allows it to be specified locally whether a parameter relates to
real-time or to user-time. For example, to define a mass source that
ramps up from a given engine-time (in crank-angle-degrees [CAD]) over a
duration in real-time, in constant/fvModels:
massSource1
{
type massSource;
points ((1 2 3));
massFlowRate
{
type scale;
scale linearRamp;
start 20 [CAD];
duration 50 [ms];
value 0.1 [g/s];
}
}
Specified units will be checked against the parameter's dimensions where
possible, and an error generated if they are not consistent. For the
dimensions to be available for this check, the code requires
modification, and work propagating this change across OpenFOAM is
ongoing. Unit conversions are still possible without these changes, but
the validity of such conversions will not be checked.
Units are no longer permitted in 'dimensions' entries in field files.
These 'dimensions' entries can now, instead, take the names of
dimensions. The names of the available dimensions are:
Standard: mass length time temperature
moles current luminousIntensity
Derived: area volume rate velocity momentum acceleration density
force energy power pressure kinematicPressure
compressibility gasConstant specificHeatCapacity
kinematicViscosity dynamicViscosity thermalConductivity
volumetricFlux massFlux
So, for example, a 0/epsilon file might specify the dimensions as
follows:
dimensions [energy/mass/time];
And a 0/alphat file might have:
dimensions [thermalConductivity/specificHeatCapacity];
*** Development Notes ***
A unit conversion can construct trivially from a dimension set,
resulting in a "standard" unit with a conversion factor of one. This
means the functions which perform unit conversion on read can be
provided dimension sets or unit conversion objects interchangeably.
A basic `dict.lookup<vector>("Umean")` call will do unit conversion, but
it does not know the parameter's dimensions, so it cannot check the
validity of the supplied units. A corresponding lookup function has been
added in which the dimensions or units can be provided; in this case the
corresponding call would be `dict.lookup<vector>("Umean", dimVelocity)`.
This function enables additional checking and should be used wherever
possible.
Function1-s and Function2-s have had their constructors and selectors
changed so that dimensions/units must be specified by calling code. In
the case of Function1, two unit arguments must be given; one for the
x-axis and one for the value-axis. For Function2-s, three must be
provided.
In some cases, it is desirable (or at least established practice), that
a given non-standard unit be used in the absence of specific
user-defined units. Commonly this includes reading angles in degrees
(rather than radians) and reading times in user-time (rather than
real-time). The primitive lookup functions and Function1 and Function2
selectors both support specifying a non-standard default unit. For
example, `theta_ = dict.lookup<scalar>("theta", unitDegrees)` will read
an angle in degrees by default. If this is done within a model which
also supports writing then the write call must be modified accordingly
so that the data is also written out in degrees. Overloads of writeEntry
have been created for this purpose. In this case, the angle theta should
be written out with `writeEntry(os, "theta", unitDegrees, theta_)`.
Function1-s and Function2-s behave similarly, but with greater numbers
of dimensions/units arguments as before.
The non-standard user-time unit can be accessed by a `userUnits()`
method that has been added to Time. Use of this user-time unit in the
construction of Function1-s should prevent the need for explicit
user-time conversion in boundary conditions and sub-models and similar.
Some models might contain non-typed stream-based lookups of the form
`dict.lookup("p0") >> p0_` (e.g., in a re-read method), or
`Umean_(dict.lookup("Umean"))` (e.g., in an initialiser list). These
calls cannot facilitate unit conversion and are therefore discouraged.
They should be replaced with
`p0_ = dict.lookup<scalar>("p0", dimPressure)` and
`Umean_(dict.lookup<vector>("Umean", dimVelocity))` and similar whenever
they are found.
Cloud functions are now not created at all during foamPostProcess. These
functions mostly usually compute state during tracking, so they cannot
produce anything useful when run as a post-process. In addition, in a
few cases, their initialisation can overwrites valid post-processing
files created at run-time.
A more "complete" system might distinguish between the few cloud
functions that can be evaluated instantaneously (e.g., sizeDistribution,
relativeVelocity, ...) and those those that cannot (e.g., fluxes,
patchCollisionDensity, ...) and only construct and execute the former
within foamPostProcess. This could be achieved with appropriate
support/funding.
In addition, volFieldValue and surfaceFieldValue have been modified so
that they do not write anything if no fields are available. This also
prevents the overwriting of valid run-time results in some cases.
functionObjects layerAverage, nearWallFields, wallHeatFlux, wallHeatTransferCoeff,
wallShearStress and forcesBase now support both the 'patches' option for which a
list of regular expressions to select the patches is specified and the new simple
'patch' option for which a single patch name is specified.
Now the HashTable underlying PtrListDictionary is used for zone lookup by name
which is a lot faster than the linear search method used previously if there are
a large number of zones.
to calculate and write the forces and moments on moving rigid bodies with
specified or calculated centre of rotation using Foam::RBD::rigidBodyMotion
respectively. The current moving centre of rotation is used in the evaluation
of the moments but does not affect the evaluation of the forces.
Class
Foam::functionObjects::movingForces
Description
Calculates the forces and moments by integrating the pressure and
skin-friction forces over a given list of patches of a moving object.
The centre of rotation (CofR) of the moving object is specified as a
Foam::Function1<vector> of time.
Member function movingForces::write() calculates the forces/moments and
writes the forces/moments into the file \<timeDir\>/movingForces.dat and bin
data (if selected) to the file \<timeDir\>/movingForces_bin.dat
Example of function object specification:
\verbatim
movingForces1
{
type movingForces;
libs ("libforces.so");
log yes;
patches (walls);
CofR
{
type sine;
amplitude (0 0.025 0);
frequency 1;
start 0;
level (0 0 0);
}
}
\endverbatim
Usage
\table
Property | Description | Required | Default value
type | Type name: movingForces | yes |
log | Write force data to standard output | no | no
patches | Patches included in the forces calculation | yes |
p | Pressure field name | no | p
U | Velocity field name | no | U
rho | Density field name (see below) | no | rho
phase | Phase name for phase-fraction | no |
CofR | Centre of rotation Foam::Function1<vector> | yes |
directForceDensity | Force density supplied directly (see below)|no|no
fD | Name of force density field (see below) | no | fD
\endtable
Bin data is optional, but if the dictionary is present, the entries must
be defined according o
\table
nBin | number of data bins | yes |
direction | direction along which bins are defined | yes |
cumulative | bin data accumulated with increasing distance | yes |
\endtable
Note
- For incompressible cases, set \c rho to \c rhoInf and provide
a \c rhoInf value corresponding to the free-stream constant density.
- If the \c phase name is specified the corresponding phase-fraction field
\c alpha.<phase> is used to filter the surface force field
before integration.
- If the force density is supplied directly, set the \c directForceDensity
flag to 'yes', and supply the force density field using the \c
fDName entry
See also
Foam::functionObject
Foam::functionObjects::forcesBase
Foam::functionObjects::fvMeshFunctionObject
Foam::functionObjects::logFiles
Foam::functionObjects::timeControl
Foam::Function1
SourceFiles
movingForces.C
Class
Foam::functionObjects::rigidBodyForces
Description
Calculates the forces and moments by integrating the pressure and
skin-friction forces over a given list of patches of a moving rigid body.
The centre of rotation (CofR) of the moving rigid object is obtained
directly from the corresponding Foam::RBD::rigidBodyMotion of the
specified body.
Member function rigidBodyForces::write() calculates the forces/moments and
writes the forces/moments into the file \<timeDir\>/rigidBodyForces.dat
and bin data (if selected) to the file \<timeDir\>/rigidBodyForces_bin.dat
Example of function object specification:
\verbatim
rigidBodyForces1
{
type rigidBodyForces;
libs ("librigidBodyForces.so");
body (hull);
patches (walls);
log yes;
}
\endverbatim
Usage
\table
Property | Description | Required | Default value
type | Type name: rigidBodyForces | yes |
log | Write force data to standard output | no | no
body | Name of the rigid body | yes |
patches | Patches included in the forces calculation | yes |
p | Pressure field name | no | p
U | Velocity field name | no | U
rho | Density field name (see below) | no | rho
phase | Phase name for phase-fraction | no |
directForceDensity | Force density supplied directly (see below)|no|no
fD | Name of force density field (see below) | no | fD
\endtable
Bin data is optional, but if the dictionary is present, the entries must
be defined according o
\table
nBin | number of data bins | yes |
direction | direction along which bins are defined | yes |
cumulative | bin data accumulated with increasing distance | yes |
\endtable
Note
- For incompressible cases, set \c rho to \c rhoInf and provide
a \c rhoInf value corresponding to the free-stream constant density.
- If the \c phase name is specified the corresponding phase-fraction field
\c alpha.<phase> is used to filter the surface force field
before integration.
- If the force density is supplied directly, set the \c directForceDensity
flag to 'yes', and supply the force density field using the \c
fDName entry
See also
Foam::functionObject
Foam::functionObjects::forcesBase
Foam::functionObjects::fvMeshFunctionObject
Foam::functionObjects::logFiles
Foam::functionObjects::timeControl
Foam::RBD::rigidBodyMotion
SourceFiles
rigidBodyForces.C
Coded functionality now supports basic un-typed substitutions from the
surrounding dictionary. For example:
value 1.2345;
#codeExecute
{
scalar s = $value;
...
};
It also now supports the more functional typed substitutions, such as:
direction (1 0 0);
#codeExecute
{
vector v = $<vector>direction;
...
};
These substitutions are now possible in all code blocks. Blocks with
access to the dictionary (e.g., #codeRead) will do a lookup which will
not require re-compilation if the value is changed. Blocks without
access to the dictionary will have the value directly substituted, and
will require recompilation when the value is changed.
This function has been changed to volume average, making it appropriate
to use on layered meshes in which the cells have non-uniform geometry
within their layers. A 'weightFields' (or 'weightField') control has
also been added, so that mass or phase weighted averages can be
performed within the layers.
This function now looks up an alphaPhi field by default and exits with
an error if the field cannot be found. In order to solve for alphaPhi a
new 'solveAlphaPhi' switch has to be set.
The documentation has been updated to reflect the fact that the VoF
solvers now store all the alphaPhi fluxes necessary for a in-phase
equation to be constructed.
The phaseScalarTransport function has been added to the damBreakLaminar
tutorial.
All property functions in the low-level templated thermo property
implementations and the high-level virtual interfaces have been made
consistent. All energies and enthalpies are lower case to denote that
they are specific quantities. Molar functions have been removed as these
are no longer used anywhere.
Description
Executes primitiveMesh::checkMesh(true) every execute time for which the
mesh changed, i.e. moved or changed topology.
Useful to check the correctness of changing and morphing meshes.
Usage
\table
Property | Description | Required | Default value
type | type name: checkMesh | yes |
noTopology | Skip checking the mesh topology | no | false
allTopology | Check all addressing | no | false
allGeometry | Check all geometry | no | false
writeSurfaces | Reconstruct and write problem faces | no | false
surfaceFormat | Format for problem faceSets | no | vtk
writeSets | Reconstruct and write problem points | no | false
setFormat | Format used to write the problem pointSets | no | vtk
nonOrthThreshold | Threshold for non-orthogonality errors | no | 70 deg
skewThreshold | Threshold for reporting skewness errors | no | 4
stopAt | Stops the run if any mesh checks fail | no | endTime
\endtable
The optional \c stopAt option may be set to
- endTime : Continue running on error
- noWriteNow : Stops the run on error without write
- writeNow : Stops the run on error and writes fields
- nextWrite : Stops the run at the next write time on error
Example of checkMesh specification:
\verbatim
checkMesh
{
type checkMesh;
libs ("libutilityFunctionObjects.so");
executeControl timeStep;
executeInterval 10;
allGeometry true;
allTopology true;
writeSurfaces true;
surfaceFormat vtk;
writeSets true;
setFormat vtk;
stopAt writeNow;
}
\endverbatim
or using the standard configuration file:
\verbatim
#includeFunc checkMesh(executeInterval=10, allGeometry=true)
\endverbatim
Now both the checkMesh utility and functionObject operate in the same manner
with the same controls, executing the same checkGeometry and checkTopology
functions from the new meshCheck library. The controls have been updated and
made more consistent and flexible, in particular by the addition of optional
user specification for the non-orthogonality and skewness error thresholds:
Application
checkMesh
Description
Checks validity of a mesh.
Usage
\b checkMesh [OPTION]
Options:
- \par noTopology
Skip checking the mesh topology
- \par -allTopology
Check all (including non finite-volume specific) addressing
- \par -allGeometry
Check all (including non finite-volume specific) geometry
- \par -meshQuality
Check against user defined (in \a system/meshQualityDict) quality
settings
- \par -region \<name\>
Specify an alternative mesh region.
- \par -writeSurfaces
Reconstruct cellSets and faceSets of problem faces and write to
postProcessing directory.
- \par -surfaceFormat <format>
Format used to write the cellSets and faceSets surfaces
e.g. vtk or ensight.
- \par -writeSets
Reconstruct pointSets of problem points nd write to
postProcessing directory.
- \par -setFormat <format>
Format used to write the pointSets
e.g. vtk or ensight.
- \par -nonOrthThreshold <threshold value in degrees>
Threshold in degrees for reporting non-orthogonality errors,
default: 70"
- \par -skewThreshold <threshold value>
Threshold for reporting skewness errors, default: 4.
Class
Foam::functionObjects::checkMesh
Description
Executes primitiveMesh::checkMesh(true) every execute time for which the
mesh changed, i.e. moved or changed topology.
Useful to check the correctness of changing and morphing meshes.
Usage
\table
Property | Description | Required | Default value
type | type name: checkMesh | yes |
noTopology | Skip checking the mesh topology | no | false
allTopology | Check all addressing | no | false
allGeometry | Check all geometry | no | false
writeSurfaces | Reconstruct and write problem faces | no | false
surfaceFormat | Format for problem faceSets | no | vtk
writeSets | Reconstruct and write problem points | no | false
setFormat | Format used to write the problem pointSets | no | vtk
nonOrthThreshold | Threshold for non-orthogonality errors | no | 70 deg
skewThreshold | Threshold for reporting skewness errors | no | 4
\endtable
Example of checkMesh specification:
\verbatim
checkMesh
{
type checkMesh;
libs ("libutilityFunctionObjects.so");
executeControl timeStep;
executeInterval 10;
allGeometry true;
allTopology true;
writeSurfaces true;
surfaceFormat vtk;
writeSets true;
setFormat vtk;
}
\endverbatim
or using the standard configuration file:
\verbatim
#includeFunc checkMesh(executeInterval=10, allGeometry=true)
\endverbatim
Warnings about initialisation of particles with locations outside of the
mesh and about the positional inaccuracy of NCC transfers are now
accumulated and printed once per time-step. This way, the log isn't
obscured by hundreds of such warnings.
Also, the pattern in which warnings are silenced after some arbitrary
number (typically 100) have been issued has been removed. This pattern
means that user viewing the log later in the run may be unaware that a
problem is still present. Accumulated warnings are concise enough that
they do not need to be silenced. They are generated every time-step, and
so remain visible throughout the log.
This change makes multiphaseEuler more consistent with other modules and
makes its sub-libraries less inter-dependent. Some left-over references
to multiphaseEulerFoam have also been removed.
When the parallel switch is set false (the default), the system call is executed
only on the master processor, if true it is executed on all processors.
Patch contributed by Stanislau Stasheuski, Aalto University.
at Function1s of time.
Underlying this new functionObject is a generalisation of the handling of the
maximum time-step in the modular solvers to allow complex user-specification of
the maximum time-step used in a simulation, not just the time-dependency
provided by fluidMaxDeltaT but functions of anything in the simulation by
creating a specialised functionObject in which the maxDeltaT function is
defined.
The chemical and combustion time-scale functionObjects adjustTimeStepToChemistry
and adjustTimeStepToCombustion have been updated and simplified using the above
mechanism.
Also provide fields and curFields functions which return the list of registered
fields not including the geometryFields and current registered fields not
including the geometryFields or old-time fields to simplify mapping code for
NCC, mesh-to-mesh mapping and load-balancing.
The purpose of these operations was unclear, and there was no
documentation or examples of their usage. The differences between these
operations behaviours for scalar and vector input seemed arbitrary.
These operations have in some cases become the subject of confusion.
They have therefore been removed.
Equivalent functionality could be easily reinstated as and when a clear
need and application becomes apparent.
Specific names have been given for expand functions. Unused functions
have been removed, and functions only used locally have been removed
from the namespace. Documentation has been corrected. Default and
alternative value handling has been removed from code template
expansion.
setFormat no longer defaults to the value of graphFormat optionally set in
controlDict and must be set in the functionObject dictionary.
boundaryFoam, financialFoam and pdfPlot still require a graphFormat entry in
controlDict but this is now read directly rather than by Time.
Class
Foam::functionObjects::checkMesh
Description
Executes primitiveMesh::checkMesh(true) every execute time for which the
mesh changed, i.e. moved or changed topology.
Useful to check the correctness of changing and morphing meshes.
Example of checkMesh specification:
\verbatim
checkMesh
{
type checkMesh;
libs ("libutilityFunctionObjects.so");
executeControl timeStep;
executeInterval 10;
}
\endverbatim
or using the standard configuration file:
\verbatim
#includeFunc checkMesh(executeInterval=10)
\endverbatim
Can be used with any solver supporting mesh-motion, in particular the movingMesh
solver module, to check the mesh quality following morphing and/or topology
change.
This avoids potential hidden run-time errors caused by solvers running with
boundary conditions which are not fully specified. Note that "null-constructor"
here means the constructor from patch and internal field only, no data is
provided.
Constraint and simple BCs such as 'calculated', 'zeroGradient' and others which
do not require user input to fully specify their operation remain on the
null-constructor table for the construction of fields with for example all
'calculated' or all 'zeroGradient' BCs.
A special version of the 'inletOutlet' fvPatchField named 'zeroInletOutlet' has
been added in which the inlet value is hard-coded to zero which allows this BC
to be included on the null-constructor table. This is useful for the 'age'
functionObject to avoid the need to provide the 'age' volScalarField at time 0
unless special inlet or outlet BCs are required. Also for isothermalFilm in
which the 'alpha' field is created automatically from the 'delta' field if it is
not present and can inherit 'zeroInletOutlet' from 'delta' if appropriate. If a
specific 'inletValue' is require or other more complex BCs then the 'alpha'
field file must be provided to specify these BCs as before.
Following this improvement it will now be possible to remove the
null-constructors from all fvPatchFields not added to the null-constructor
table, which is most of them, thus reducing the amount of code and maintenance
overhead and making easier and more obvious to write new fvPatchField types.
gcc-13 has new code checking and warning mechanisms which are useful but not
entirely robust and produce many false positives, particularly with respect to
local references:
warning: possibly dangling reference to a temporary
This commit resolves many of the new warning messages but the above false
warnings remain. It is possible to switch off this warning but as it also
provides some useful checks it is currently left on.
This is useful to write results before a case fails due to uncontrollable
automatic time-step reduction, usually caused by unstable pressure-velocity
coupling.
Class
Foam::functionObjects::stopAtTimeStep
Description
Stops the run if the time-step drops below the specified value in seconds
and optionally write results before stopping.
The following actions are supported:
- noWriteNow
- writeNow (default)
- nextWrite
Examples of function object specification:
\verbatim
stop
{
type stopAtTimeStep;
libs ("libutilityFunctionObjects.so");
minDeltaT 1e-8;
action writeNow;
}
\endverbatim
will write the fields and stop if the time-step drops below 1e-8s.
Usage
\table
Property | Description | Required | Default value
type | type name: stopAtTimeStep | yes |
minDeltaT | Minimum time-step [s] | yes |
action | Action executed | no | writeNow
\endtable
