Defining the Air and Water Phases

You simulate the flow of two materials: air and water. As water transitions to different flow regimes, each of which is modeled by a different multiphase model, you require a water phase for each multiphase model type. The air phase remains continuous and is modeled by the VOF model only.

Initially, the entire computation domain is filled with the continuous air phase. The following table summarizes the flow regimes and their models.

Flow Regime Multiphase Model Phase
Free surface water jet with large resolved droplets and ligaments VOF model

Eulerian air phase

Eulerian water phase
Water droplets Lagrangian Multiphase model Lagrangian water phase
Water film Fluid Film model Fluid film water phase

Each water phase requires the same material properties and the same equation of state.

To define the air and water phases:

  1. Create the Eulerian air phase:
    1. Right-click the Continua > Physics 1 > Models > Multiphase > Phases node and select New.
    2. Rename the Phase 1 node as Air.
    3. Right-click the Air > Models node and select the following models:
      Group Box Model
      Material Gas
      Equation of State Constant Density
    4. Click Close.
  2. Create the Eulerian water phase:
    1. Right-click the Multiphase > Phases node and select New.
    2. Rename the Phase 1 node as Water.
    3. Right-click the Water > Models node and select the following models:
      Group Box Model
      Material Liquid
      Equation of State Constant Density
    4. Click Close.
  3. Create the Lagrangian water droplets phase:
    1. Right-click the Physics 1 > Models > Lagrangian Multiphase > Lagrangian Phases node and select New > Free-stream Phase.
    2. Rename the phase as Water Droplets.
    3. Right-click the Water Droplets > Models node and select the following models:
      Group Box Model
      Particle Type Material Particles
      Material Liquid
      Equation of State Constant Density
      Optional Models Energy
      Two-Way Coupling
    4. Click Close.
  4. Create the water film phase:
    1. Right-click the Physics 1 > Models > Fluid Film > Fluid Film Phases node and select New.
    2. Rename the phase as Water Film.
    3. Right-click the Water Film node and select the following models:
      Table 1.
      Group Box Model
      Space Three Dimensional
      Material Liquid
      Equation of State Constant Density
      Viscous Regime Laminar
    4. Click Close.
  5. To initialize the computational domain with air, select the Physics 1 > Initial Conditions > Volume Fraction node and set Value to [1.0, 0.0].
  6. Save the simulation.