BeetstraDrag

Syntax

Defined in couplingProperties dictionary.

forceModels
(
    BeetstraDrag
);
BeetstraDragProps
{
    velFieldName         "U";
    voidfractionFieldName "voidfraction";
    granVelFieldName     "Us";
    gravityFieldName     "g";
    useFilteredDragModel;
    useParcelSizeDependentFilteredDrag;
    rhoParticle          scalar;
    dPrim                scalar;
    k                    scalar;
    aLimit               scalar;
    aExponent            scalar;
    voidfractionInterpolationType word;
    UInterpolationType   word;
    splitImplicitExplicit;
    forceStokesLaw       switch;
    filtDragSimpleCorrectionFactor scalar;
    suppressProbe        switch;

    // (optional) forceSubModel switches
    treatForceExplicit   switch;
    implForceDEM         switch;
    verbose              switch;
    interpolation        switch;
    scaleDrag            scalar;
    scaleDH              scalar;
};

  • velFieldName = name of the finite volume fluid velocity field (default: “U”)

  • voidfractionFieldName = name of the finite volume voidfraction field (default: “voidfraction”)

  • granVelFieldName = name of the finite volume granular velocity field (Make sure this velocity field is updated before the forces are computed!) (default: “Us”)

  • gravityFieldName = name of the gravity variable (default: “g”)

  • useFilteredDragModel = switch for using a coarse-grid version of the Beetstra drag model which takes grid-size effects into account. Keyword only setting, activated if present. (default: off)

  • useParcelSizeDependentFilteredDrag = switch for using a coarse-grid version of the Beetstra drag model which takes parcel-size effects into account and will forces the switch useFilteredDragModel. Keyword only setting, activated if present. (default = off)

  • rhoParticle = particle density (required if useFilteredDragModel activated)

  • dPrim = particle diameter of reference particle (required if useFilteredDragModel activated)

  • k = factor for parcels size effect (default: 0.0; must be >=0; recommended value = 0.05; only relevant if useParcelSizeDependentFilteredDrag is active)

  • aLimit = prefactor for limiting filtered drag correction at high particle volume fractions (default: 0.0; must be >=0; recommended value for dilute flows = 0.0, recommended value for dense flows = 1.0; only relevant if useParcelSizeDependentFilteredDrag is active)

  • aExponent = exponent for limiting filtered drag correction at high particle volume fractions (default: 1.0; must be >=1, recommended value = 1.0; only relevant if useParcelSizeDependentFilteredDrag is active)

  • voidfractionInterpolationType = interpolation type for voidfraction field (default: “cellPoint”)

  • UInterpolationType = interpolation type for velocity field (default: “cellPointFace”)

  • filtDragSimpleCorrectionFactor = drag correction factor (default: 1)

  • forceStokesLaw = imposes Stokes drag law (default: false)

  • suppressProbe = can be used to suppress the output of the probe model (default: false)

This forceModel reads the following forceSubModel switches and overwrites the defaults as indicated in parentheses:

  • scaleDrag

  • scaleDH

  • treatForceExplicit

  • implForceDEM

  • verbose

  • interpolation

  • scalarViscosity

  • useFilteredDragModel

  • useParcelSizeDependentFilteredDrag

  • useCorrectedVoidage

Examples

forceModels
(
    BeetstraDrag
);
BeetstraDragProps
{
    splitImplicitExplicit;
    granVelFieldName         "Us";
    velFieldName             "U";
    gravityFieldName         "g";
    voidfractionFieldName    "voidfraction";
    interpolation            true;
//    useFilteredDragModel;
//    useParcelSizeDependentFilteredDrag ;
//    rhoParticle            1500.;
//    dPrim                  150e-6;
//    k                      0.05;
//    aLimit                 0.0;
//    aExponent              1.0;
}

Description

The force model performs the calculation of forces (e.g. fluid-particle interaction forces) acting on each DEM particle. The BeetstraDrag model is a model that calculates the particle based drag force following the correlation of Beetstra (2007, AIChE J 53:489-501).

The filtered drag model is based on the work by Radl and Sundaresan (AIChE Annual meeting 2012, paper 273c. For the details of the filtered drag model (to be activated with useFilteredDragModel and useParcelSizeDependentFilteredDrag), see the separate documentation separate documentation.

The flag splitImplicitExplicit enables the implicit/explicit force splitting based on fluctuating fluid and particle velocities as documented in the paper by Radl et al. (Effective Drag Law for Parcel-BasedApproaches What Can We Learn from CFD-DEM?, Proceedings of ECCOMAS 2012, Vienna).

Restrictions

This model is strictly valid only for monodisperse gas-particle flows, the polydisperse model of Beetstra (2007) has NOT been incorporated!