periodicPressure

Syntax

Defined in couplingProperties dictionary.

forceModels
(
    periodicPressure
);
periodicPressureProps
{
    gravityFieldName "g";
    voidfractionFieldName "voidfraction";
    mode             "word";
    targetVelocity   vector;
    p                scalar;
    i                scalar;
    avMixtureDensity scalar;
};

  • gravityFieldName = name of gravity field

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

  • mode = keyword for operation mode, choose controlled or mixtureDensity

  • targetVelocity = target ensemble average particle velocity (for monodisperse systems) - only for mode controlled

  • p = proportional constant for controller - only for mode controlled

  • i = integral constant for controller - only for mode controlled

  • avMixtureDensity = average density of the mixture in the domain - only for mode mixtureDensity

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

  • scaleDrag

  • scaleDH

  • verbose

Examples

forceModels
(
    periodicPressure
);
periodicPressureProps
{
    gravityFieldName "g";
    voidfractionFieldName "voidfraction";
    mode "controlled";
    targetVelocity (0. 0. 0.);
    p 2500;
    i 1;
}

Description

The force model calculates a force field following two different modi:

  1. controlled and

  2. mixtureDensity, which can be used to transform fluid pressure gradient to dynamic pressure gradient which is necessary for periodic boundaries.

With mode controlled the force field is set in a way, that the ensemble average particle velocity reaches a target velocity. With modus mixtureDensity, a force field rhoMix*g*voidfraction is calculated. The force is passed to the explicitCoupleSource model via the setSourceField() function. For theoretical background see Radl, Girardi and Sundaresan (2012): “Effective drag law for parcel-based approaches – what can we learn from CFD-DEM?”, ECCOMAS 2012, Vienna.)

The following images show a brief summary of the equations and an overview of how the force on the CFD and DEM side is calculated:

_images/forceModel_periodicPressure_1.png _images/forceModel_periodicPressure_2.png _images/forceModel_periodicPressure_3.png

Restrictions

None.