Lagrangian/Eulerian Passive Scalar Interactions

Lagrangian phases can interact both with other Lagrangian phases and with phases of other types using Multiphase Interaction models. Both Lagrangian and Eulerian frameworks give the option of using passive scalars as user-defined variables of arbitrary value, assigned to fluid phases or individual particles.

These scalars are passive because they do not affect the physical properties of the simulation. An intuitive way to think of passive scalars is as marker paint on a particle or parcel, or marker dye in a fluid, but with numerical values instead of colors, and with no appreciable mass or volume.

The Passive Scalar Interaction model allows transfer of values between passive scalars on Lagrangian and Eulerian phases. It becomes available when a Lagrangian and an Eulerian phase both have passive scalars defined.

To set up an interaction between Lagrangian and Eulerian passive scalars:

  1. Right-click the [physics continuum] > Models node and, from the Optional Models group box, select Passive Scalar Interaction.
    The Multiphase Interaction node appears.
  2. Right-click the Multiphase Interaction > Phase Interactions node and select New > [phase 1] > [phase 2]. This adds a Phase Interaction node, with the Passive Scalar Interaction phase interaction model selected automatically.
  3. Right-click the [phase interaction] > Models node and select Passive Scalar Transfer.
  4. Right-click the Passive Scalar Transfer > Passive Scalar Transfers node and select New > Area Weighted or Volume Weighted. Nodes for these appear under the Passive Scalar Transfer > Passive Scalar Transfers node. You can create interactions of any type for a given pair of phases.
  5. Select the Area Weighted 1 or the Volume Weighted 1 node and set the following properties:
    Property Setting
    Phase 1 Material The passive scalar in the Lagrangian phase.
    Phase 2 Material The passive scalar in the Eulerian phase (physics continuum).


  6. Expand the Area Weighted 1 or Volume Weighted 1 node and set the following properties:
    Node Setting
    Coefficient 1 to 2 Specify the parameter control rate of transfer from the Phase 1 Material to the Phase 2 Material for area-weighted transfer.
    Coefficient 2 to 1

    Specify the parameter control rate of transfer from the Phase 2 Material to the Phase 1 Material for area-weighted transfer.
    Coefficient Specify the parameter control rate between the Phase 1 Material and the Phase 2 Material for volume-weighted transfer.