which provides a very convenient mechanism to process and write any temporary
fields created during a time-step, either within models the construction of
equations and matrices or any other intermediate processing step within an
OpenFOAM application. The cached fields can relate to physical properties in
models, e.g. the generation term or other terms in the turbulence models, or
numerical, e.g. the limiters used on convection schemes. This mechanism
provides a new very powerful non-intrusive way of analysing the internals of an
OpenFOAM application for diagnosis and general post-processing which cannot be
easily achieved by any other means without adding specific diagnostics code to
the models or interest and recompiling.
For example to cache the kEpsilon:G field in
tutorials/incompressible/simpleFoam/pitzDaily add the dictionary entry
cacheTemporaryObjects
(
grad(k)
kEpsilon:G
);
to system/controlDict and to write the field add a writeObjects entry to the
functions list:
functions
{
writeCachedObjects
{
type writeObjects;
libs ("libutilityFunctionObjects.so");
writeControl writeTime;
writeOption anyWrite;
objects
(
grad(k)
kEpsilon:G
);
}
#includeFunc streamlines
}
If a name of a field which in never constructed is added to the
cacheTemporaryObjects list a waning message is generated which includes a useful
list of ALL the temporary fields constructed during the time step, e.g. for the
tutorials/incompressible/simpleFoam/pitzDaily case:
--> FOAM Warning : Could not find temporary object dummy in registry region0
Available temporary objects
81
(
(((0.666667*C1)-C3)*div(phi))
div(phi)
(interpolate(nuEff)*magSf)
surfaceIntegrate(phi)
(interpolate(DepsilonEff)*magSf)
((interpolate(((1|((1|(1|A(U)))-H(1)))-(1|A(U))))*snGrad(p))*magSf)
grad(p)
((interpolate(nuEff)*magSf)*snGradCorr(U))
(interpolate((1|((1|(1|A(U)))-H(1))))*magSf)
((1|((1|(1|A(U)))-H(1)))-(1|A(U)))
((Cmu*sqr(k))|epsilon)
interpolate(HbyA)
interpolate(DkEff)
interpolate(U)
phiHbyA
weights
div(((interpolate((1|((1|(1|A(U)))-H(1))))*magSf)*snGradCorr(p)))
(phiHbyA-flux(p))
MRFZoneList:acceleration
average(interpolate(max(epsilon,epsilonMin)))
div(((interpolate(DepsilonEff)*magSf)*snGradCorr(epsilon)))
nuEff
kEpsilon:G
grad(k)
interpolate((1|((1|(1|A(U)))-H(1))))
(nuEff*dev2(T(grad(U))))
grad(U)
interpolate(epsilon)
(phi*linearUpwind::correction(U))
((interpolate(DepsilonEff)*magSf)*snGradCorr(epsilon))
grad(k)Cached
(HbyA-((1|((1|(1|A(U)))-H(1)))*grad(p)))
pos0(phi)
-div((nuEff*dev2(T(grad(U)))))
H(1)
interpolate(k)
((nut|sigmak)+nu)
snGrad(p)
(0.666667*div(phi))
surfaceIntegrate(((interpolate((1|((1|(1|A(U)))-H(1))))*magSf)*snGradCorr(p)))
DepsilonEff
(1|A(U))
surfaceIntegrate(((interpolate(DepsilonEff)*magSf)*snGradCorr(epsilon)))
limitedLinearLimiter(epsilon)
surfaceIntegrate(((interpolate(DkEff)*magSf)*snGradCorr(k)))
grad(epsilon)
(interpolate(DkEff)*magSf)
div(((interpolate(DkEff)*magSf)*snGradCorr(k)))
surfaceSum(magSf)
((1|A(U))-(1|((1|(1|A(U)))-H(1))))
(1|((1|(1|A(U)))-H(1)))
((interpolate((1|((1|(1|A(U)))-H(1))))*magSf)*snGradCorr(p))
mag(div(phi))
surfaceSum((magSf*interpolate(max(epsilon,epsilonMin))))
interpolate(DepsilonEff)
-grad(p)
snGradCorr(p)
interpolate(p)
interpolate(max(epsilon,epsilonMin))
dev(twoSymm(grad(U)))
surfaceIntegrate((phi*linearUpwind::correction(U)))
(magSf*interpolate(max(epsilon,epsilonMin)))
limitedLinearLimiter(k)
(nut+nu)
HbyA
max(epsilon,epsilonMin)
surfaceIntegrate(((interpolate(nuEff)*magSf)*snGradCorr(U)))
surfaceIntegrate(phiHbyA)
DkEff
(((C1*kEpsilon:G)*epsilon)|k)
(mag(S)+2.22507e-308)
(((1|A(U))-(1|((1|(1|A(U)))-H(1))))*grad(p))
((nut|sigmaEps)+nu)
((interpolate(DkEff)*magSf)*snGradCorr(k))
(nut*(dev(twoSymm(grad(U)))&&grad(U)))
interpolate(nuEff)
((C2*epsilon)|k)
interpolate((nuEff*dev2(T(grad(U)))))
(epsilon|k)
div(phiHbyA)
div(((interpolate(nuEff)*magSf)*snGradCorr(U)))
)
Multiple regions are also supported by specifying individual region names in a
cacheTemporaryObjects dictionary, e.g. in the
tutorials/heatTransfer/chtMultiRegionFoam/heatExchanger case
cacheTemporaryObjects
{
air
(
kEpsilon:G
);
porous
(
porosityBlockage:UNbr
);
}
functions
{
writeAirObjects
{
type writeObjects;
libs ("libutilityFunctionObjects.so");
region air;
writeControl writeTime;
writeOption anyWrite;
objects (kEpsilon:G);
}
writePorousObjects
{
type writeObjects;
libs ("libutilityFunctionObjects.so");
region porous;
writeControl writeTime;
writeOption anyWrite;
objects (porosityBlockage:UNbr);
}
}
Improvements to existing functionality
--------------------------------------
- MPI is initialised without thread support if it is not needed e.g. uncollated
- Use native c++11 threading; avoids problem with static destruction order.
- etc/cellModels now only read if needed.
- etc/controlDict can now be read from the environment variable FOAM_CONTROLDICT
- Uniform files (e.g. '0/uniform/time') are now read only once on the master only
(with the masterUncollated or collated file handlers)
- collated format writes to 'processorsNNN' instead of 'processors'. The file
format is unchanged.
- Thread buffer and file buffer size are no longer limited to 2Gb.
The global controlDict file contains parameters for file handling. Under some
circumstances, e.g. running in parallel on a system without NFS, the user may
need to set some parameters, e.g. fileHandler, before the global controlDict
file is read from file. To support this, OpenFOAM now allows the global
controlDict to be read as a string set to the FOAM_CONTROLDICT environment
variable.
The FOAM_CONTROLDICT environment variable can be set to the content the global
controlDict file, e.g. from a sh/bash shell:
export FOAM_CONTROLDICT=$(foamDictionary $FOAM_ETC/controlDict)
FOAM_CONTROLDICT can then be passed to mpirun using the -x option, e.g.:
mpirun -np 2 -x FOAM_CONTROLDICT simpleFoam -parallel
Note that while this avoids the need for NFS to read the OpenFOAM configuration
the executable still needs to load shared libraries which must either be copied
locally or available via NFS or equivalent.
New: Multiple IO ranks
----------------------
The masterUncollated and collated fileHandlers can now use multiple ranks for
writing e.g.:
mpirun -np 6 simpleFoam -parallel -ioRanks '(0 3)'
In this example ranks 0 ('processor0') and 3 ('processor3') now handle all the
I/O. Rank 0 handles 0,1,2 and rank 3 handles 3,4,5. The set of IO ranks should always
include 0 as first element and be sorted in increasing order.
The collated fileHandler uses the directory naming processorsNNN_XXX-YYY where
NNN is the total number of processors and XXX and YYY are first and last
processor in the rank, e.g. in above example the directories would be
processors6_0-2
processors6_3-5
and each of the collated files in these contains data of the local ranks
only. The same naming also applies when e.g. running decomposePar:
decomposePar -fileHandler collated -ioRanks '(0 3)'
New: Distributed data
---------------------
The individual root directories can be placed on different hosts with different
paths if necessary. In the current framework it is necessary to specify the
root per slave process but this has been simplified with the option of specifying
the root per host with the -hostRoots command line option:
mpirun -np 6 simpleFoam -parallel -ioRanks '(0 3)' \
-hostRoots '("machineA" "/tmp/" "machineB" "/tmp")'
The hostRoots option is followed by a list of machine name + root directory, the
machine name can contain regular expressions.
New: hostCollated
-----------------
The new hostCollated fileHandler automatically sets the 'ioRanks' according to
the host name with the lowest rank e.g. to run simpleFoam on 6 processors with
ranks 0-2 on machineA and ranks 3-5 on machineB with the machines specified in
the hostfile:
mpirun -np 6 --hostfile hostfile simpleFoam -parallel -fileHandler hostCollated
This is equivalent to
mpirun -np 6 --hostfile hostfile simpleFoam -parallel -fileHandler collated -ioRanks '(0 3)'
This example will write directories:
processors6_0-2/
processors6_3-5/
A typical example would use distributed data e.g. no two nodes, machineA and
machineB, each with three processes:
decomposePar -fileHandler collated -case cavity
# Copy case (constant/*, system/*, processors6/) to master:
rsync -a cavity machineA:/tmp/
# Create root on slave:
ssh machineB mkdir -p /tmp/cavity
# Run
mpirun --hostfile hostfile icoFoam \
-case /tmp/cavity -parallel -fileHandler hostCollated \
-hostRoots '("machineA" "/tmp" "machineB" "/tmp")'
Contributed by Mattijs Janssens
The logic governing function objects' ability to change the time-step
has been modified so that it is compatible with the time-step adjustment
done in the Time class. The behaviour has been split into a method which
sets the step directly, and another which moidifies the time until the
next write operation (i.e., the time that the solver "aims" for).
This fixes an issue where the adjustments in Time and the function
objects interfere and cause the time step to decrease exponentially down
to machine precision. It also means that the set-time-step function
object now does not break the adjustable run-time setting.
This resolves bug report https://bugs.openfoam.org/view.php?id=2820
An unintended change in the running-state logic was introduced by commit
9a35ce69. The running state should only be re-evaluated when in the
simulation is not ending. The "execute/end" function object invocation
should not be permitted to change the running state. The simulation
should always end if this state is reached.
In early versions of OpenFOAM the scalar limits were simple macro replacements and the
names were capitalized to indicate this. The scalar limits are now static
constants which is a huge improvement on the use of macros and for consistency
the names have been changed to camel-case to indicate this and improve
readability of the code:
GREAT -> great
ROOTGREAT -> rootGreat
VGREAT -> vGreat
ROOTVGREAT -> rootVGreat
SMALL -> small
ROOTSMALL -> rootSmall
VSMALL -> vSmall
ROOTVSMALL -> rootVSmall
The original capitalized are still currently supported but their use is
deprecated.
chtMultiRegionSimpleFoam needs to check whether or not the simulation is
at the end. To facilitate this, a Time::running method has been added.
The Time::run method was being used for this purpose, but this lead to
function objects being executed multiple times.
This resolves bug report https://bugs.openfoam.org/view.php?id=2804
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.
Time: call functionObject 'execute()' and 'end()' for last time-step
Now the operation of functionObject 'end()' call is consistent between running and post-processing
the equivalent functionality is provided by the writeRegisteredObject
functionObject in a MUCH simpler, easier and extensible manner.
functionObject: Removed the now redundant 'timeSet' function.
to have the prefix 'write' rather than 'output'
So outputTime() -> writeTime()
but 'outputTime()' is still supported for backward-compatibility.
Also removed the redundant secondary-writing functionality from Time
which has been superseded by the 'writeRegisteredObject' functionObject.
Simplified and generalized the handling of functionObjects which fail to
construct by removing them from the list rather than maintaining an
"enabled" switch in each functionObject.
Avoids unnecessary increases in precision during intermediate steps for
cases with adjustable time-step which may require very high precision to
represent the time name.
