Setting Up the Boundary Conditions and the Shell Region

Since you expect the water film to form on the floor only, the floor is where you create the shell region for the Fluid Film model. Only after you create the shell region you can specify that all Lagrangian water droplets impacting the floor are converted to fluid film.

When you create a shell region on the floor boundary, Simcenter STAR-CCM+ exposes a boundary condition mode in which you specify the conversion of droplets to fluid film.

The VOF water jet enters the computational domain at the inflow boundary with a velocity of 5 m/s. The top and sides of the domain are specified as pressure boundaries that permit backflow. These boundary types were already defined in the starting simulation file.

To set up the boundary conditions and the shell region:

  1. Create the shell region for the water film:
    1. Right-click the Regions > Fountain > Boundaries > Floor node and select Create Shell Region.
      The Floor shell node is added as a new region.

    2. Select the Regions > Floor shell node and set Continuum to Water Film.
  2. Edit the Regions > Fountain > Boundaries > Inflow > Physics Values node and set the following properties:
    Node Property Setting
    Velocity Magnitude Value 5 m/s
    Volume Fraction Value [0.0, 1.0]
  3. Multi-select the Physics Values > Volume Fraction nodes of the Sides and the Sky boundaries and set Value to [1.0, 0.0].


  4. Expand the Continua > Physics 1 > Models > Lagrangian Multiphase node.
  5. Select the Lagrangian Phases > Water Droplets > Boundary Conditions > Fluid-Film Boundary > Physics Conditions > Mode node and set Active Mode to Fluid Film.


  6. Similarly, select the Boundary Conditions > Wall > Physics Conditions > Mode node and set Active Mode to VOF Conversion.
  7. Save the simulation.