Workflow guidelines

Here the suggested workflows for using eddylicious in conduction with various solvers are presented. Basically, whatever solver is used, the following steps have to be performed.

• Specifying the geometry of the inlet for eddylicious.

• Choosing an output format that is compatible with the used solver.

• Generating the inflow fields by running the python script associated with the chosen inflow generation method.

• Setting up the solver to read in boundary data from the hard drive.

Using eddylicious with OpenFOAM

Important

This offering is not approved or endorsed by OpenCFD Limited, producer and distributor of the OpenFOAM software and owner of the OPENFOAM® and OpenCFD® trade marks.

Specifying the geometry of the inlet

Specifying the geometry boils down to producing the list of face centres located at the inlet boundary. The coordinates of the face centres can be used using the postProcess utility shipped with OpenFOAM.

A new file should be created in the system directory, the name is arbitrary, for example, inletSurface. In the file a function object of type surfaces should be created. It is improtant that th name of the function object is the same as that of the file. Inside the function object one should define a surface of type patch, and specify the name inlet patch. It is better to turn off triangulation to preserve the original geometry. Choose foam as the write format for surface.

Even though we are only interested in the geometry, a field for sampling has to be chosen. Any field can be chosen, besides for the velocity field U. This is because the sample utility will attempt to read in the field, and, since we didn’t generate it yet, the field-values simply don’t exist yet.

An example of the function object for a case with the inlet patch named inlet can look something like this.

inletSurface
{
    type surfaces;
    fields
    (
       p
    );
    surfaceFormat foam;
    interpolationScheme cellPoint;
    surfaces
    (
        inlet
        {
            type patch;
            patches (inlet);
            interpolate false;
            triangulate false;
        }
    );
}

The geometry, then be extracted with postProcess -func inletSurface The produced file can be read using the foamFile inflow geometry reader. The path to the produced faceCenters file should be provided. This is done by adding the following lines to the configuration file for the inflow generation script.

inflowGeometryReader    foamFile
inflowGeometryPath      "/path/to/faceCenters/file"

Reading the inflow fields from OpenFOAM

OpenFOAM has a special boundary condition that allows reading boundary data from a file, it is called timeVaryingMappedFixedValue. A tutorial, which takes advantage of this boundary condition, is shipped with OpenFOAM. It can be found under tutorials/incompressible/simpleFoam/pitzDailyExptInlet/.

The boundary condition is quite flexible. If needed, interpolation in space will be used to obtain the vales at the face centres from the values at the provided points. Linear interpolation in time is also supported.

Let inlet be the name of the patch for which the inflow fields are generated. Then the following entry should be found in the U file.

inlet
{
    type            timeVaryingMappedFixedValue;
    offset          (0 0 0);
    setAverage      off;
    perturb         0;
}

Setting perturb to 0 is important, since this option perturbs the location of the points.

In order to generate the inflow fields the OpenFOAM native format should be used for writing the velocity fields to the hard drive.

Note that, for a large time-span, the amount of files written to disk become extremely large. To rectify this issue, a modified version of timeVaryingMappedFixedValue that reads all the data from a single HDF5 file is available. For more information regarding the structure of the file see The HDF5 file format.

The modified boundary condition is called timeVaryingMappedHDF5FixedValue and can be downloaded at https://bitbucket.org/lesituu/timevaryingmappedhdf5fixedvalue

If this boundary condition is used the entry in the U file should look as follows.

inlet
{
    type            timeVaryingMappedHDF5FixedValue;
    setAverage      false;
    perturb         0;
    offset          (0 0 0);
    hdf5FileName    nameofthehdf5file.hdf5;
    hdf5PointsDatasetName    points;
    hdf5SampleTimesDatasetName    time;
    hdf5FieldValuesDatasetName    velocity;
}