Defining Eulerian Phases

A Eulerian phase in Simcenter STAR-CCM+ represents a distinct physical substance – the phase material – that is modeled in a Eulerian framework. Two materials constitute two different Eulerian phases. The definition of a Eulerian phase includes the set of models that apply to the phase material and the relevant material properties.

A Eulerian phase model plays the same role in a Eulerian phase as a conventional model does in a physics continuum. It defines how a physical phenomenon in a phase is represented, what the primary variables of the simulation are and what mathematical formulation is used to generate the solution. As a minimum, each Eulerian phase requires a material model, an equation of state model, and a viscous regime model.

You can create new phases in the simulation tree, or directly in the Physics Model Selection dialog.

To define a Eulerian phase:

  1. In the simulation tree or the Physics Model Selection dialog, right-click the Multiphase > Eulerian Phases node and select New.
    The new phase, Phase 1, is added under the Eulerian Phases node. You can rename the phase at any time.
  2. If you created the phase in the simulation tree, right-click [phase] > Models and click Select Models.

    If you created the phase in the Physics Model Selection dialog, select the new phase.

    The right panel of the Phase Model Selection dialog displays the available phase models.

Eulerian phase model selection is not identical to model selection for a continuum, since Eulerian phases implicitly inherit certain model choices such as those for space, time, and motion. The choice of material and equation of state models available in the dialog depends on the physics models that you selected at the continuum level.

  1. In the Phase Model Selection dialog, select the appropriate models in order:

    Group Box

    Model

    Material

    • Gas
    • Liquid
    • Particle

      Defines a dispersed particle phase that is modeled using the Eulerian Multiphase approach. To model the effect of particle-particle interaction within the phase, use the Solid Pressure Force model.

      This option is available for the Eulerian Multiphase (EMP) model only.

    • Multi-Component Gas (not available for the Dispersed Multiphase (DMP) model)
    • Multi-Component Liquid (not available for the Dispersed Multiphase (DMP) model)

    For information on working with single-component materials, see Managing single-component materials. For information on working with multi-component materials, see Managing multi-component materials. This latter section includes details on adding individual mixture components.

    Reaction Regime

    • Non-reacting
    • Reacting

    This option applies to multi-component phase materials only.

    Equation of State

    A Eulerian phase requires its own Equation of State model to define how the density of the material is computed.

    These models are the same as the corresponding models for the Simcenter STAR-CCM+ simulation in general, except that they apply to the Eulerian phase only rather than throughout the continuum.

    See General Equation of State Models.

    • Constant Density

      This is the only available EOS for the Dispersed Multiphase (DMP) model.

    • Ideal Gas

      This model is intended for use in low Mach number flows (typically for Mach numbers less than 0.3)

    • Polynomial Density
    • Real Gas
    • User Defined EOS

    Viscous Regime

    If the Laminar or Inviscid models are activated in the continuum, the Eulerian phases are automatically set to the same viscous regime and cannot be changed.

    If the Turbulent model is activated in the continuum, the Turbulent viscous regime is selected by default. However, you can deselect the Turbulent model and activate the Laminar model instead.

    Viscous Regime is not applicable for the Dispersed Multiphase (DMP) model.

    Energy

    If the Phase Coupled Fluid Energy is selected in the physics continuum for Eulerian Multiphase, select one of the following for each phase:

    • Segregated Fluid Temperature
    • Segregated Fluid Enthalpy
    If the Segregated Multiphase Temperature or the Segregated Fluid Isothermal is selected in the Volume of Fluid (VOF) or Mixture Multiphase (MMP) physics continuum, the Energy model is selected automatically for each phase.

    For Dispersed Multiphase (DMP), select Segregated Fluid Temperature for each phase, if the following are selected for the physics continuum:

    • Coupled Energy or Segregated Fluid Enthalpy for Two-Phase Thermodynamic Equilibrium.
    • Segregated Fluid Temperature or Segregated Fluid Isothermal for Volume of Fluid (VOF) and Mixture Multiphase (MMP), and Flow Model is selected in the DMP phase models.

    Optional Models

    For more details on the optional models that apply to your simulation, refer to the relevant workflow:

  2. When you have selected the appropriate phase models, do one of the following:
    • To return to the simulation tree at the location from which the Physics Model Selection dialog was opened, click Close.
    • To return to the simulation tree at a particular phase, select the appropriate phase in the left panel, right-click and click Select in Simulation.

    Nodes corresponding to the selected models appear under the Models node for the Eulerian phase.

The default material model appears within the Models node for the phase.

To replace the default material with something more appropriate:

  1. Right-click the material node and select Replace with. In the Replace Material dialog, select the required material, and then click OK.
Specify the material properties of each phase.
  1. For each phase, expand the [phase] > Models > [phase material] > Material Properties node, select the individual material property nodes, and modify the property values to suit your requirements.