DNS

Basic Solvers

Combustion Solvers

Compressible Flow Solvers

Electromagnetic Solvers

Financial Solvers

Heat Transfer Solvers

Incompressible Flow Solvers

Discrete Methods Solvers

Lagrangian Solvers

Multiphase Solvers

Stress-Analysis

Advanced Mesh Manipulation

Mesh Conversion

Mesh Generation

Mesh Manipulation

Error Estimation

Miscellaneous Utilities

Parallel Processing

Post-Processing

Pre-Processing

Surface File Manipulation

Thermophysical Utilities

FreeFOAM Helper Scripts

Below you find an overview of the small helper scripts provided by FreeFOAM.

Global Configuration Files

Unfortunately the OpenFOAM library (on which FreeFOAM builds) and some applications require the following files to be present for start-up:

It finds them in the following places (in the specified order, picking the first hit):

where the versions in above directory names depend on the version of the FreeFOAM application to be run.

Locating the API documentation

All FreeFOAM applications accept the options -doc and -srcDoc. The former locates and displays the API documentation of the application, the latter the source code. This, however, requires that FreeFOAM is able to locate the API documentation and knows which program to use for display.

By default FreeFOAM uses the API documentation provided on http://freefoam.sf.net/doc/API because most users will not want to install the sizeable documentation package. The method FreeFOAM uses to locate the documentation files is via index files which are conventional FreeFOAM dictionaries. Each of them contains an entry docDir specifying the documentation root location (such as http://freefoam.sf.net/doc/API) and a dictionary called docFiles mapping the application name to the names of the corresponding HTML documentation and source page.

These documentation indices are found by querying the list Documentation::doxyDocIndices in the global controlDict file. If multiple documentation indices are specified, the first index that provides documentation for the given application is picked.

Displaying the API documentation

FreeFOAM can automatically open a browser window displaying the HTML documentation for you. The entry Documentation::docBrowser in the global controlDict can be used to change which program is used for this. In this string the token %f gets replaced by the filename to open.

Debug, Info and Optimisation Switches

The lists DebugSwitches, InfoSwitches and OptimisationSwitches in the global controlDict file determine some global run-time behaviour of FreeFOAM. The entries in DebugSwitches can be set to 1 for more verbose output in the specified class.

The InfoSwitches::writePrecision setting determines the write precision in the output to the terminal (i.e. not the output written to files). Whether a job-info file should be created can be specified by enabling InfoSwitches::writeJobeInfo.

For files that are modifieable during run-time (e.g. to change the interval at which the output is created), FreeFOAM compares the modification times of these files in order to determine whether they have to be re-read. The setting OptimisationSwitches::fileModificationSkew determines the minimum modification-time difference in seconds for a file to be considered changed.

The setting OptimisationSwitches::commsType determines whether inter-process communications are either blocking, scheduled or nonBlocking.

OptimisationSwitches::floatTransfer causes to convert double values to float before transferring them through the communications library. This saves some bandwidth at the loss of accuracy.

The sum operation across processors can be executed either in a linear or a tree fashion. Especially for a large number of processors, tree-summation is significantly faster. The threshold at which to switch from linear to tree-summation is determined by OptimisationSwitches::nProcsSimpleSum.

Physical Constants

Plugin Search Path

FreeFOAM very often relies on dynamically loading libraries (a.k.a plugins). If the library name is given as an absolute path, FreeFOAM tries to load it directly. To locate libraries specified just by their name or with a relative path, FreeFOAM first tries to find the library in one of the directories specified in the list LibrarySearchPaths in the global controlDict and, if the library was not found, falls back to the mechanism provided by your operating system (i.e. for Linux systems this would be the LD_LIBRARY_PATH and the default search path).

Selecting the Parallel Communications Library

Both, FreeFOAM and OpenFOAM abstract the parallel operations into the Pstream library, making it rather simple to firstly switch between parallel implementations and secondly port the software to a new communications library. However, FreeFOAM uses a much more flexible mechanism of determining which Pstream implementation library to use than OpenFOAM. The latter does this by adjusting the LD_LIBRARY_PATH environment variable. As FreeFOAM wants to be a well behaved Linux citizen, this is not an option. Instead, FreeFOAM dynamically loads the desired Pstream library at startup (i.e. as a plug-in). The following list details how FreeFOAM determines what library to load (if at all):

Please note that this library is also considered to be a plugin, and thus is located in the same way as described above.

After FreeFOAM (possibly) loaded the library, it will try to instantiate concrete implementations of the abstract base classes PstreamImpl, IPstreamImpl and OPstreamImpl. Which classes are to be instantiated is determined as follows:

This means that one can create a global controlDict file containing (among other things) something like the following:

PstreamImplementation
{
    //configName dummy;
    configName mpi;

    dummy
    {
        library libdummyPstream.so;
        Pstream dummyPstreamImpl;
        OPstream dummyOPstreamImpl;
        IPstream dummyIPstreamImpl;
    }

    mpi
    {
        library libmpiPstream.so;
        Pstream mpiPstreamImpl;
        OPstream mpiOPstreamImpl;
        IPstream mpiIPstreamImpl;
    }
}

This way the administrator can provide a global controlDict in the FreeFOAM installation. Every user can then override that controlDict by supplying her own file in her home directory as detailed above. In order to select a particular Pstream implementation for a specific communications library, the user can then either adjust the PstreamImplementation::configName entry in the global controlDict file, set the FREEFOAM_PSTREAM_CONFIG variable or, for full control, set the variables FREEFOAM_PSTREAM_LIBRARY, FREEFOAM_PSTREAM_CLASS, FREEFOAM_IPSTREAM_CLASS and FREEFOAM_OPSTREAM_CLASS.

Starting of a Parallel Job

Some of the tutorial scripts need to run FreeFOAM applications in parallel. However, how to do so differs strongly from system to system and between parallel communication libraries. This is why the command line to start an application in parallel is configureable in the parRunTemplate setting. ${NPROCS}, ${PAROPTS}, ${APPLICATION} and ${ARGS} are placeholders for the number of processors to use, options for the parallel communications system, the application to run and its arguments, respectively. Note that the -parallel option is NOT included in ${ARGS}.