The OpenFOAM solvers begin all runs by setting up a database. The database
controls I/O and, since output of data is usually requested at intervals of time
during the run, time is an inextricable part of the database. The controlDict
dictionary sets input parameters essential for the creation of the database. The
keyword entries in controlDict are listed in 4.4. Only the time control and
writeInterval entries are truly compulsory, with the database taking
default values indicated by † in 4.4 for any of the optional entries that are
omitted.
Time control
startFrom
Controls the start time of the simulation.
- firstTime
Earliest time step from the set of time directories.
- startTime
Time specified by the startTime keyword entry.
- latestTime
Most recent time step from the set of time directories.
startTime
Start time for the simulation with startFrom startTime;
stopAt
Controls the end time of the simulation.
- endTime
Time specified by the endTime keyword entry.
- writeNow
Stops simulation on completion of current time step and writes
data.
- noWriteNow
Stops simulation on completion of current time step and does not
write out data.
- nextWrite
Stops simulation on completion of next scheduled write time,
specified by writeControl.
endTime
End time for the simulation when stopAt endTime; is specified.
deltaT
Time step of the simulation.
Data writing
writeControl
Controls the timing of write output to file.
- timeStep†
Writes data every writeInterval time steps.
- runTime
Writes data every writeInterval seconds of simulated time.
- adjustableRunTime
Writes data every writeInterval seconds of simulated
time, adjusting the time steps to coincide with the writeInterval
if necessary -- used in cases with automatic time step adjustment.
- cpuTime
Writes data every writeInterval seconds of CPU time.
- clockTime
Writes data out every writeInterval seconds of real time.
writeInterval
Scalar used in conjunction with writeControl described above.
purgeWrite
Integer representing a limit on the number of time directories that
are stored by overwriting time directories on a cyclic basis. Example
of , and purgeWrite 2;: data written into 2
directories, 6 and 7, before returning to write the data at 8 in
6, data at 9 into 7, etc.
To disable the time directory limit, specify purgeWrite 0;†
For steady-state solutions, results from previous iterations can be
continuously overwritten by specifying purgeWrite 1;
writeFormat
Specifies the format of the data files.
- ascii†
ASCII format, written to writePrecision significant figures.
- binary
Binary format.
writePrecision
Integer used in conjunction with writeFormat described above,
6† by default
writeCompression
Specifies the compression of the data files.
- uncompressed
No compression.†
- compressed
gzip compression.
timeFormat
Choice of format of the naming of the time directories.
- fixed
where the number of s is set by timePrecision.
- scientific
where the number of s is set by
timePrecision.
- general†
Specifies scientific format if the exponent is less than -4 or
greater than or equal to that specified by timePrecision.
timePrecision
Integer used in conjunction with timeFormat described above,
6† by default
graphFormat
Format for graph data written by an application.
- raw†
Raw ASCII format in columns.
- gnuplot
Data in gnuplot format.
- xmgr
Data in Grace/xmgr format.
- jplot
Data in jPlot format.
Data reading
runTimeModifiable
yes†/no switch for whether dictionaries, e.g.controlDict, are
re-read by OpenFOAM at the beginning of each time step.
Run-time loadable functionality
libs
List of additional libraries (on $LD_LIBRARY_PATH) to be loaded
at run-time, e.g.( "libUser1.so" "libUser2.so" )
functions
List of functions, e.g.probes to be loaded at run-time; see examples
in $FOAM_TUTORIALS
† denotes default entry if associated keyword is omitted.
Table 4.4:
Keyword entries in the controlDict dictionary.
Example entries from a controlDict dictionary are given below:
, 
and 
in
into 
where the number of 
s is set by 
where the number of 
s is set by