Defining the Liquid Phase for the Melting-Solidification Model

You define the liquid phase and apply the Melting-Solidification model.

You model the freezing water as a Eulerian phase in Simcenter STAR-CCM+. The properties of water come from the material database, with some modifications to suit the problem. For this tutorial, the value of latent heat is reduced so that freezing takes place sooner than it would with the default value. For a real case, however, leave the value at its original setting.

To define the liquid phase for the Melting-Solidification model:

Create the H2O phase.
  1. In the Physics 1 continuum, right-click the Models > Multiphase > Phases node and create a new phase.
  2. Rename the Phase 1 node to H2O.
  3. For the H2O phase, select the following models in order:

    Group Box

    Model

    Enabled Models

    Energy (selected automatically)

    Turbulent (selected automatically)

    Material

    Liquid

    Equation of State

    Constant Density

    Optional Models

    Melting-Solidification

  4. In the H2O Model Selection dialog, in the left pane, select the Physics 1 node.
  5. In the Physics 1 Model Selection dialog, in the Optional Models group box, select Melting-Solidification Flow Stop.
  6. Click Close.
  7. Select the Phases > H2O > Models > Melting-Solidification node and set Under-Relaxation Factor to 0.1.

You set the solid volume fraction threshold above which flow is stopped in the fluid phase.

  1. Select the H2O > Models > Liquid > H2O > Material Properties > Flowability Threshold > Constant node and set Value to 0.999.

The thermal conductivity of H2O varies with phase and temperature. For this simulation, assume that the thermal conductivity is constant for each phase.

The thermal conductivity of ice is 2.33 W / m K while the conductivity of H2O is 0.620271 W/m K. Use a conditional expression to set the conductivity of the H2O phase. Set the conductivity to 2.33 W/m K when the temperature is less than or equal to 273 K, and 0.620271 W / m K for higher temperatures.

Create a step function to set the conductivity of H2O:

  1. Right-click the Automation > Field Functions node and select New > Scalar from the pop-up menu.
  2. Rename the User Field Function 1 to Variable Thermal Conductivity.
  3. Select the Variable Thermal Conductivity node and set the following properties:
    Property Setting
    Function Name Variable Thermal Conductivity
    Definition (${Temperature} <= 273.) ? 2.33 : 0.620271
  4. Set Dimensions to Power/Length-Temperature by filling the Dimensions dialog with the following values:


    The Properties window appears as shown.



Use this variable thermal conductivity for the H2O phase.
  1. Edit the Phases > H2O > Models > Liquid > H2O > Material Properties node and set the following properties:
    Node Property Setting
    Thermal Conductivity Method Field Function
    Thermal Conductivity > Field Function Scalar Function Variable Thermal Conductivity
    Latent Heat of Fusion > Constant Value 100000.0 J/kg
    Liquidus Temperature > Constant Value 273.0 K
    Solidus Temperature > Constant Value 273.0 K
  2. Save the simulation.