Setting Up Phase Interactions

The interactions between the dispersed phase and the background (continuous phase), between the dispersed phase and a VOF phase, and between the dispersed phase and a fluid film, are set up as phase interactions. You set up these phase interactions under the Multiphase Interaction node.

In a typical scenario, with one-way coupling, the continuous phase interacts with the dispersed phase through drag force and heat transfer. The dispersed phase has no influence on the continuous phase. However, when two-way coupling is activated, heat is transferred between the dispersed phase and the continuous phase with overall heat conservation. Likewise, the drag force applies in both directions.

The dispersed phase interacts with the fluid film phase by impingement of droplets from the dispersed phase into the fluid film and stripping of droplets from the fluid film into the dispersed phase.

You can use the Discrete Quadrature S-Gamma model for the dispersed phase to model the particles size change due to breakup and coalescence.

Dispersed Phase - Continuous Phase Interaction

The continuous phase can be a VOF phase or the physics continuum. If the dispersed phase interacts with two or more VOF phases, you specify a separate DMP-VOF phase interaction for each VOF phase.

To specify the interaction between the dispersed phase and a continuous phase:

  1. Right-click the Multiphase Interaction > Phase Interactions node and select New > [DMP Phase] > [Continuous Phase].

    The appropriate phase interaction model is added under the Phase Interaction > Models node:

    • DMP-Physics Continuum Interaction

      Uses the mixture properties (such as density, dynamic viscosity, and specific heat) when calculating source contributions. Used for all material models except Volume of Fluid (VOF).

    • DMP-VOF Phase Interaction

      Uses the phase properties when calculating source contributions for each VOF phase. The phase source contributions (such as drag and heat transfer) are weighted by the corresponding VOF volume fraction. Used for the Volume of Fluid (VOF) material model only.

  2. Select the appropriate optional models.

    The image below shows the Phase Interaction Model Selection dialog. This example is for the DMP-Physics Continuum Interaction model, the optional models for the DMP-VOF Phase Interaction model are the same, except that the Non-Equilibrium Condensation is not applicable. Additionally, the Impingement interaction model is available with DMP-VOF phase interactions.

    To include the effects of breakup and coalescence on the predicted size distribution, you select S-Gamma Breakup, and S-Gamma Coalescence models in the Phase Interaction Model Selection dialog.



    The available optional models are:
    Heat Transfer See Modeling Heat Transfer.
    Impingement See DMP-VOF Impingement.
    S-Gamma Breakup See Discrete Quadrature S-Gamma Phase Interaction Models Reference.
    S-Gamma Coalescence
    Multiphase Material
    Interaction Length Scale Specify the method for defining the interaction length scale. You can select a constant value or set as the Sauter Mean Diameter when the S-gamma model is activated for the dispersed phase.
    Non-Equilibrium Condensation See Non-Equilibrium Condensation Model Reference.
    Drag Force See Drag Force Model Reference.
  3. Click Close.

    The selected models are added under the Phase Interaction > Models node.

    The example below is for the DMP-VOF Phase Interaction model.



Dispersed Phase - Fluid Film Phase Interaction

To specify the interaction between the dispersed phase and the fluid film phase:

  1. Right-click the Multiphase Interaction > Phase Interactions node and select New > [DMP Phase] > [Fluid Film Phase].
  2. Open the Phase Interaction Model Selection dialog and select the appropriate optional models.
    The available optional models are:
    Impingement See Impingement Model Reference.
    Multiphase Material
    Stripping See Stripping Model Reference.
  3. Click Close.

    The selected models are added under the Phase Interaction > Models node.