smoothingModel constDiffAndTemporalSmoothing command

Syntax

Defined in dictionary depending on the application.

smoothingModel constDiffAndTemporalSmoothing;
constDiffAndTemporalSmoothingProps
{
    lowerLimit                    number1;
    upperLimit                    number2;
    smoothingLength               lengthScale;
    smoothingLengthReferenceField lengthScaleRefField;
    smoothingStrength             smoothingStrength;
    correctBoundary               switch1;
    verbose;
}

  • number1 = scalar fields will be bound to this lower value

  • number2 = scalar fields will be bound to this upper value

  • lengthScale = length scale over which the exchange fields will be smoothed out

  • lengthScaleRefField = length scale over which reference fields (e.g., the average particle velocity) will be smoothed out. Should be always larger than lengthScale. If not specified, will be equal to lengthScale.

  • smoothingStrength = control parameter gamma for the smoothing, lower value yields stronger smoothing (gamma = 1 results in an equal contribution from the un-smoothed and smoothed fields)

  • correctBoundary = (optional, default false) activate to use purely temporal smoothing on the boundary field, avoids interpolation errors near the domain boundary

  • verbose = (optional, default false) flag for debugging output

Examples

constDiffAndTemporalSmoothingProps
{
    lowerLimit       0.1;
    upperLimit       1e10;
    smoothingLength  1500e-6;
    smoothingLengthReferenceField 9000e-6;
    referenceField   "p";
    gamma            1.0;
}

Description

The constDiffAndTemporalSmoothing model is a smoothing model that combines the spacial smoothing of constDiffSmoothing and the temporal smoothing of temporalSmoothing for the relaxation of a desired quantity. This model can be used to filter out high-frequency fluctuations (e.g. numerical noise) controlled via the smoothing length and the temporal smoothing strength parameter gamma.

For more details, see Vångö et al. (2018) and Nijssen et al. (2020).

(Vångö2018) M. Vångö, S. Pirker, T. Lichtenegger. (2018): “Unresolved CFD-DEM modeling of multiphase flow in densely packed particle beds”, Applied Mathematical Modelling

(Nijssen2020) T.M.J. Nijssen, J.A.M. Kuipers, J. van der Stel, A.T. Adema, K.A. Buist. (2020): “Complete liquid-solid momentum coupling for unresolved CFD-DEM simulations”, International Journal of Multiphase Flow

Restrictions

This model is tested in a limited number of flow situations.