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.
This is a CHT case which uses snappyHexMesh. It is a tutorial, in the
traditional sense, in that it has been designed for training purposes.
It does not rely on changeDictionary, surface utilities, or extensive
scripting.
This work was supported by Colin Moughton, at Strix
Multi-region PIMPLE controls have been applied to the chtMultiRegionFoam
solver, and a transonic option has been implemented.
The new PIMPLE controls let the solver operate SIMPLE mode. The
utilisation of library solution and convergence control functionality
has significantly reduced the amount of code in the solver. The
chtMultiRegionSimpleFoam solver has also been made obsolete, and has
therefore been removed.
A few changes will be necessary to convert an existing
chtMultiRegionSimpleFoam case to chtMultiRegionFoam. All the SIMPLE
sub-dictionaries in the system/<regions>/fvSolution will need to be
renamed PIMPLE. The system/fvSolution file will also need an empty
PIMPLE sub-dictionary. In addition, additional "<variable>Final" solver
and relaxation entries will be needed. For a steady case, adding a
wildcard ending, ".*", to the variable names should be sufficient.
Solution parameters appropriate for a steady case are shown below:
solvers
{
"p_rgh.*"
{
solver GAMG;
tolerance 1e-7;
relTol 0.01;
smoother DIC;
maxIter 10;
}
"(U|h|e|k|epsilon).*"
{
solver PBiCGStab;
preconditioner DILU;
tolerance 1e-7;
relTol 0.1;
}
}
PIMPLE
{
// ...
}
relaxationFactors
{
fields
{
"p_rgh.*" 0.7;
}
equations
{
"U.*" 0.5;
"(h|e).*" 0.3;
"(k|epsilon).*" 0.2;
}
}
This work was supported by Fabian Buelow, at Evonik
Tobias Holzmann provided cases for testing the convergence controls
Using the noSlip boundary condition for rotating wall in an MRF region
interferes with post-processing by resetting the wall velocity to 0 rather than
preserving the value set by the MRF zone.
A pureMixture can now be specified in a reacting solver. This further
enhances compatibility between non-reacting and reacting solvers.
To achieve this, mixtures now have a typeName function of the same form
as the lower thermodyanmic models. In addition, to avoid name clashes,
the reacting thermo make macros have been split into those that create
entries on multiple selection tables, and those that just add to the
reaction thermo table.
When an OpenFOAM simulation runs in parallel, the data for decomposed fields and
mesh(es) has historically been stored in multiple files within separate
directories for each processor. Processor directories are named 'processorN',
where N is the processor number.
This commit introduces an alternative "collated" file format where the data for
each decomposed field (and mesh) is collated into a single file, which is
written and read on the master processor. The files are stored in a single
directory named 'processors'.
The new format produces significantly fewer files - one per field, instead of N
per field. For large parallel cases, this avoids the restriction on the number
of open files imposed by the operating system limits.
The file writing can be threaded allowing the simulation to continue running
while the data is being written to file. NFS (Network File System) is not
needed when using the the collated format and additionally, there is an option
to run without NFS with the original uncollated approach, known as
"masterUncollated".
The controls for the file handling are in the OptimisationSwitches of
etc/controlDict:
OptimisationSwitches
{
...
//- Parallel IO file handler
// uncollated (default), collated or masterUncollated
fileHandler uncollated;
//- collated: thread buffer size for queued file writes.
// If set to 0 or not sufficient for the file size threading is not used.
// Default: 2e9
maxThreadFileBufferSize 2e9;
//- masterUncollated: non-blocking buffer size.
// If the file exceeds this buffer size scheduled transfer is used.
// Default: 2e9
maxMasterFileBufferSize 2e9;
}
When using the collated file handling, memory is allocated for the data in the
thread. maxThreadFileBufferSize sets the maximum size of memory in bytes that
is allocated. If the data exceeds this size, the write does not use threading.
When using the masterUncollated file handling, non-blocking MPI communication
requires a sufficiently large memory buffer on the master node.
maxMasterFileBufferSize sets the maximum size in bytes of the buffer. If the
data exceeds this size, the system uses scheduled communication.
The installation defaults for the fileHandler choice, maxThreadFileBufferSize
and maxMasterFileBufferSize (set in etc/controlDict) can be over-ridden within
the case controlDict file, like other parameters. Additionally the fileHandler
can be set by:
- the "-fileHandler" command line argument;
- a FOAM_FILEHANDLER environment variable.
A foamFormatConvert utility allows users to convert files between the collated
and uncollated formats, e.g.
mpirun -np 2 foamFormatConvert -parallel -fileHandler uncollated
An example case demonstrating the file handling methods is provided in:
$FOAM_TUTORIALS/IO/fileHandling
The work was undertaken by Mattijs Janssens, in collaboration with Henry Weller.
For example the actuationDiskSource fvOption may now be specified
disk1
{
type actuationDiskSource;
fields (U);
selectionMode cellSet;
cellSet actuationDisk1;
diskDir (1 0 0); // Orientation of the disk
Cp 0.386;
Ct 0.58;
diskArea 40;
upstreamPoint (581849 4785810 1065);
}
rather than
disk1
{
type actuationDiskSource;
active on;
actuationDiskSourceCoeffs
{
fields (U);
selectionMode cellSet;
cellSet actuationDisk1;
diskDir (1 0 0); // Orientation of the disk
Cp 0.386;
Ct 0.58;
diskArea 40;
upstreamPoint (581849 4785810 1065);
}
}
but this form is supported for backward compatibility.
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 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.
e.g. in tutorials/heatTransfer/buoyantSimpleFoam/externalCoupledCavity/0/T
hot
{
type externalCoupledTemperature;
commsDir "${FOAM_CASE}/comms";
file "data";
initByExternal yes;
log true;
value uniform 307.75; // 34.6 degC
}
Previously both 'file' and 'fileName' were used inconsistently in different
classes and given that there is no confusion or ambiguity introduced by using
the simpler 'file' rather than 'fileName' this change simplifies the use and
maintenance of OpenFOAM.
using a run-time selectable preconditioner
References:
Van der Vorst, H. A. (1992).
Bi-CGSTAB: A fast and smoothly converging variant of Bi-CG
for the solution of nonsymmetric linear systems.
SIAM Journal on scientific and Statistical Computing, 13(2), 631-644.
Barrett, R., Berry, M. W., Chan, T. F., Demmel, J., Donato, J.,
Dongarra, J., Eijkhout, V., Pozo, R., Romine, C. & Van der Vorst, H.
(1994).
Templates for the solution of linear systems:
building blocks for iterative methods
(Vol. 43). Siam.
See also: https://en.wikipedia.org/wiki/Biconjugate_gradient_stabilized_method
Tests have shown that PBiCGStab with the DILU preconditioner is more
robust, reliable and shows faster convergence (~2x) than PBiCG with
DILU, in particular in parallel where PBiCG occasionally diverges.
This remarkable improvement over PBiCG prompted the update of all
tutorial cases currently using PBiCG to use PBiCGStab instead. If any
issues arise with this update please report on Mantis: http://bugs.openfoam.org
Added the option '-subDict' to specify a sub-dictionary if multiple
replacement sets are present in the same file. This also provides
backward compatibility by setting '-subDict dictionaryReplacement'
To re-use existing 'sampleDict' files simply add the following entries:
type sets;
libs ("libsampling.so");
and run
postProcess -func sampleDict
It is probably better to also rename 'sampleDict' -> 'sample' and then run
postProcess -func sampleDict
In most boundary conditions, fvOptions etc. required and optional fields
to be looked-up from the objectRegistry are selected by setting the
keyword corresponding to the standard field name in the BC etc. to the
appropriate name in the objectRegistry. Usually a default is provided
with sets the field name to the keyword name, e.g. in the
totalPressureFvPatchScalarField the velocity is selected by setting the
keyword 'U' to the appropriate name which defaults to 'U':
Property | Description | Required | Default value
U | velocity field name | no | U
phi | flux field name | no | phi
.
.
.
However, in some BCs and functionObjects and many fvOptions another
convention is used in which the field name keyword is appended by 'Name'
e.g.
Property | Description | Required | Default value
pName | pressure field name | no | p
UName | velocity field name | no | U
This difference in convention is unnecessary and confusing, hinders code
and dictionary reuse and complicates code maintenance. In this commit
the appended 'Name' is removed from the field selection keywords
standardizing OpenFOAM on the first convention above.
- Avoids the need for the 'OutputFilterFunctionObject' wrapper
- Time-control for execution and writing is now provided by the
'timeControlFunctionObject' which instantiates the processing
'functionObject' and controls its operation.
- Alternative time-control functionObjects can now be written and
selected at run-time without the need to compile wrapped version of
EVERY existing functionObject which would have been required in the
old structure.
- The separation of 'execute' and 'write' functions is now formalized in the
'functionObject' base-class and all derived classes implement the
two functions.
- Unnecessary implementations of functions with appropriate defaults
in the 'functionObject' base-class have been removed reducing
clutter and simplifying implementation of new functionObjects.
- The 'coded' 'functionObject' has also been updated, simplified and tested.
- Further simplification is now possible by creating some general
intermediate classes derived from 'functionObject'.
See http://www.openfoam.org/mantisbt/view.php?id=2076
- .org is the file extension for emacs org-mode as well
- .orig is more to the point (.org isn't always recognized as "original")
- .original is too long, although more consistent with the convention
of source code file naming
Update script contributed by Bruno Santos
The boundary conditions of HbyA are now constrained by the new "constrainHbyA"
function which applies the velocity boundary values for patches for which the
velocity cannot be modified by assignment and pressure extrapolation is
not specified via the new
"fixedFluxExtrapolatedPressureFvPatchScalarField".
The new function "constrainPressure" sets the pressure gradient
appropriately for "fixedFluxPressureFvPatchScalarField" and
"fixedFluxExtrapolatedPressureFvPatchScalarField" boundary conditions to
ensure the evaluated flux corresponds to the known velocity values at
the boundary.
The "fixedFluxPressureFvPatchScalarField" boundary condition operates
exactly as before, ensuring the correct flux at fixed-flux boundaries by
compensating for the body forces (gravity in particular) with the
pressure gradient.
The new "fixedFluxExtrapolatedPressureFvPatchScalarField" boundary
condition may be used for cases with or without body-forces to set the
pressure gradient to compensate not only for the body-force but also the
extrapolated "HbyA" which provides a second-order boundary condition for
pressure. This is useful for a range a problems including impinging
flow, extrapolated inlet conditions with body-forces or for highly
viscous flows, pressure-induced separation etc. To test this boundary
condition at walls in the motorBike tutorial case set
lowerWall
{
type fixedFluxExtrapolatedPressure;
}
motorBikeGroup
{
type fixedFluxExtrapolatedPressure;
}
Currently the new extrapolated pressure boundary condition is supported
for all incompressible and sub-sonic compressible solvers except those
providing implicit and tensorial porosity support. The approach will be
extended to cover these solvers and options in the future.
Note: the extrapolated pressure boundary condition is experimental and
requires further testing to assess the range of applicability,
stability, accuracy etc.
Henry G. Weller
CFD Direct Ltd.
in decomposeParDict.
This default number of processors may be overridden by the new "-np"
option to runParallel which must be specified before the application
name e.g.:
runParallel -np 4 pisoFoam
so that the specification of the name and dimensions are optional in property dictionaries.
Update tutorials so that the name of the dimensionedScalar property is
no longer duplicated but optional dimensions are still provided and are
checked on read.
by introducing rational base-classes rather than using the hideous
'switch' statement. Further rationalization of the cell-selection
mechanism will be implemented via an appropriate class hierarchy to
replace the remaining 'switch' statement.
Mesh-motion is currently handled very inefficiently for cellSets and not
at all for inter-region coupling. The former will be improved when the
cell-selection classes are written and the latter by making the
meshToMesh class a MeshObject after it has been corrected for mapFields.
fvOptions does not have the appropriate structure to support MRF as it
is based on option selection by user-specified fields whereas MRF MUST
be applied to all velocity fields in the particular solver. A
consequence of the particular design choices in fvOptions made it
difficult to support MRF for multiphase and it is easier to support
frame-related and field related options separately.
Currently the MRF functionality provided supports only rotations but
the structure will be generalized to support other frame motions
including linear acceleration, SRF rotation and 6DoF which will be
run-time selectable.
Description
Specify an etc file to include when reading dictionaries, expects a
single string to follow.
Searches for files from user/group/shipped directories.
The search scheme allows for version-specific and
version-independent files using the following hierarchy:
- \b user settings:
- ~/.OpenFOAM/\<VERSION\>
- ~/.OpenFOAM/
- \b group (site) settings (when $WM_PROJECT_SITE is set):
- $WM_PROJECT_SITE/\<VERSION\>
- $WM_PROJECT_SITE
- \b group (site) settings (when $WM_PROJECT_SITE is not set):
- $WM_PROJECT_INST_DIR/site/\<VERSION\>
- $WM_PROJECT_INST_DIR/site/
- \b other (shipped) settings:
- $WM_PROJECT_DIR/etc/
An example of the \c \#includeEtc directive:
\verbatim
#includeEtc "etcFile"
\endverbatim
The usual expansion of environment variables and other constructs is
retained.
For multi-region cases the default location of blockMeshDict is now system/<region name>
If the blockMeshDict is not found in system then the constant directory
is also checked providing backward-compatibility
