Setting Up a Simulation with Evaporation and Condensation

This section describes how to set up a simulation with evaporation and condensation.

To use Simcenter STAR-CCM+ for solving problems that involve evaporation and condensation:

  1. Select the physics models that are required for a VOF multiphase simulation.
  2. Define the multi-component Eulerian phases.
  3. Select the Evaporation/Condensation model in a phase interaction.

Defining Evaporation and Condensation Mixture Components

For a simulation with evaporation and condensation in Simcenter STAR-CCM+, create two Eulerian Phases. The primary phase must be a liquid, and the other phase must be a gas. Both must be multi-component phases.

  1. Create a Eulerian phase, and select Multi-Component Gas from the Material group.
  2. Select Non-reacting from the Reaction Regime group.
    The Species model is selected automatically.
  3. Select an appropriate model from the Equation of State group.
  4. Right-click the Multi-Component Gas > Gas Components node and choose Select Mixture Components...
  5. In the Select Mixture Components dialog which appears, select the gas components required.

    The Evaporation/Condensation model in Simcenter STAR-CCM+ requires the gas mixture to include at least one inert component. However, the mass fraction of this inert phase can be very small; typically 1e-3 or 1e-4, but a mass fraction of 0 is still valid. In the example below, Air, Heptane, and Octane are selected, and Air is the inert component.



  6. Repeat the creation steps for a second phase where evaporation is likely to occur, but select Multi-Component Liquid as the material.
  7. Select only the liquid components in the Select Mixture Components dialog.

    In this example, Heptane and Octane are selected.

    The simulation tree appears as shown below.



    The saturation pressure is available from the Material Properties of each liquid component. The latent heat of vaporization is incorporated automatically through the heat of formation property, available for both gas and liquid components.

The final step in setting up an evaporation/condensation case is to define the evaporation/condensation phase interaction.

Selecting the Evaporation/Condensation Model from a Phase Interaction

The Evaporation and Condensation model can be applied only to a single phase interaction where you define all of the liquid and vapor phase components. You cannot define the liquid and vapor phase components for the Evaporation and Condensation model in multiple phase interactions.

To select the Evaporation and Condensation model:

  1. Create a phase interaction with the Primary Phase as the multi-component liquid and the Secondary Phase as the multi-component gas.
  2. Open the Phase Interaction Model Selection dialog and choose the Evaporation/Condensation model from the Optional Models group.

    The Evaporation/Condensation node appears in the simulation tree.



Set component pairs using the properties of the Evaporation/Condensation model node:

  1. Select the Evaporation/Condensation model node.
  2. Click the ellipsis to the right of the Connectivity property in the Properties window.
  3. In the Connectivity dialog that appears, match the liquid and vapor phase components using the drop-down menus provided.