The extractEulerianParticles function object generates particle size information from Eulerian calculations, e.g. VoF. It derives spherical particles by interrogating the Eulerian phase fraction field.


Operand Type Location
input - -
input - -
output file - -
output field 1 scalarField $OUTPUT/d
output field 2 scalarField $OUTPUT/soi
output field 3 labelField $OUTPUT/tag
output field 4 vectorField $OUTPUT/U

where $OUTPUT=$FOAM_CASE/<time>/lagrangian/eulerianParticleCloud.


Example of the extractEulerianParticles function object by using functions sub-dictionary in system/controlDict file:

    // Mandatory entries (unmodifiable)
    type            extractEulerianParticles;
    libs            (fieldFunctionObjects);

    // Mandatory entries (runtime modifiable)
    faceZone        f0;
    alpha           alpha.water;

    // Optional entries (runtime modifiable)
    alphaThreshold  0.1;
    nLocations      0;
    U               U;
    rho             rho;
    phi             phi;
    minDiameter     1e-30;
    maxDiameter     1e30;

    // Optional (inherited) entries
    writePrecision  8;
    writeToFile     true;
    useUserTime     true;
    region          region0;
    enabled         true;
    log             true;
    timeStart       0;
    timeEnd         1000;
    executeControl  timeStep;
    executeInterval 1;
    writeControl    timeStep;
    writeInterval   1;

where the entries mean:

Property Description Type Required Default
type Type name: extractEulerianParticles word yes -
libs Library name: fieldFunctionObjects word yes -
faceZone Name of faceZone used as collection surface word yes -
alpha Name of phase indicator field word yes -
alphaThreshold Threshold for alpha field scalar no 0.1
nLocations Number of injection bins to generate label no 0
U Name of velocity field word no U
rho Name of density field word no rho
phi Name of flux field word no phi
minDiameter Minimum diameter scalar no SMALL
maxDiameter Maximum diameter scalar no GREAT

The inherited entries are elaborated in:

Usage by the postProcess utility is not available.

Notes on entries

The faceZone defines the particle collection surface, at which the phase fraction field, alpha is interpolated to identify the particle bounds.

Each isolated Eulerian region is converted into the equivalent spherical particle by default. Alternatively, the nLocations entry can be used to agglomerate the face zone to define a set of collection faces across which particle information is gathered. This can be useful to the derive particle spatial distribution. faces into a set of collection zones, for which

Stored properties

Reduced data

The following data are stored by the function object, and can be used by other function objects:

  • nCollectedParticles: number of particles collected
  • collectedVolume: volume of collected particles
  • nDiscardedParticles: number of discarded particles
  • discardedVolume: volume of discarded particles

Sample output

Further information


Source code: