StokesSpheroidDrag

Syntax

Defined in couplingProperties dictionary.

particleShapeType multisphere;
forceModels
(
    StokesSpheroidDrag
);
StokesSpheroidDragProps
{
    velFieldName     word;
    voidfractionFieldName word;
    granVelFieldName word;
    cDragInertial    scalar;
    ReInertialSwitchOn scalar;
    useVoidfractionCorrection Switch;
    legacyDiameter   Switch;

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

  • 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 average particle velocity field (default: “Us”)

  • cDragInertial = inertial drag coefficent (if -1, only viscous drag is considered). (default: -1)

  • ReInertialSwitchOn = the particle Re by ReInertialSwitchOn is used to fade in the inertial drag for higher Reynolds numbers (default: 100, used only if cDragInertial > 0)

  • useVoidfractionCorrection = use voidfraction correction: \Xi = 3.7 - 0.65 \exp(-\frac{1}{2}(1.5 - \log_10(\mathit{Rep}))^2); \mathit{correction} = voidfraction^{2 - \Xi} (default: true)

  • legacyDiameter = use legacy diameter calculation taking into account the number of spheres (true) or purely base on volume of particles type as determined by Aspherix (false). (default: true)

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

  • scaleDrag

  • scaleDH

  • treatForceExplicit

  • implForceDEM (default: true)

  • verbose

  • interpolation

  • anisotropicDrag

  • implTorqueDEM

Examples

particleShapeType multisphere;
forceModels
(
    StokesSpheroidDrag
);
StokesSpheroidDragProps
{
    interpolation           true;
}

Description

The StokesSpheroidDrag model calculates the particle based drag force assuming creeping flow around a spheroidal particle following Lindström and Uesaka (2007 Phys Fluids) and the theory as described by Kim and Karilla (Microhydrodynamics: Principles and Selected Applications).

Note

The particles’ shape, orientation, and rotation rate will be considered in the calculation, so the user has to ensure that Aspherix holds this information This means that an appropriate particle_shape must be selected in the Aspherix input script, e.g. multisphere or superquadric. Also, the user has to ensure that these quantities are correctly updated and that the torque on the particle is considered in the Aspherix calculation.

Restrictions

Note

Only for multisphere and superquadric particles.

Note

For multisphere particles the particle templates should be perfectly linear rods of spheres. Otherwise this model may be inaccurate.