Setting up Solidified Mass Removal

By default, the Melting-Solidification model treats the fluid film as a homogeneous mixture of solidified mass and liquid. For a liquid material, the Relative Solid Volume Fraction is used to represent the amount of solid. For a liquid-solid-gas material, the corresponding field function is the Mass Fraction of the solid component. You can configure the model so that the solidified mass is removed from the fluid film: all of the mass that remains in the fluid film is liquid.

A major application of the Melting-Solidification model for fluid films is airfoil icing. An important aspect of airfoil icing is run-back: the flow of liquid water over the layer of recently solidified ice. In airfoil icing simulations, it is important to represent the geometry of the airfoil as a combination of the airfoil and the ice layer, as the geometry has a significant effect on the flow field. Accurately modeling the flow field is essential for predicting aerodynamic characteristics such as lift and drag, and also for modeling the self-reinforcing impact on the ice accretion rate itself. To allow the Melting-Solidification model to track the liquid-solid interface, you activate the Solidified Film Removal model.

To ensure that the geometry is accurately represented, you can use the Morpher to adjust the surface of the solidified volume when the solidified mass is removed. If the Morpher is activated and configured, the wall morphs to model the surface of the solidified volume. You can specify the density of the solid; Simcenter STAR-CCM+ uses the specified density to compute the morphing that is applied to the surface of the solidified mass. If the Morpher is not activated, or is not correctly configured, the solidified mass is removed with no effect on the geometry of the wall.

To set up solidified mass removal:

  1. In the fluid film phase, activate the Solidified Film Removal model.

    The Solid Density node appears under the Solidified Film Removal node. If you are using the Morpher to model the surface of the solidified mass, you can specify the density of the solid.

  2. Select the Solidified Film Removal > Solid Density node and select the Method to use for specifying the density of the solid.
    See Solid Density Properties.
  3. If necessary, specify the appropriate constant value, or select the appropriate field function.

To activate and configure the Morpher:

  1. Activate the Morpher.

    To set up a Morphing motion, right-click the Tools > Motions node and click New > Morphing.

  2. Apply the Morphing motion to the fluid region.

    Under the Regions > [Fluid] > Physics Values > Motion Specification node, set the Motion to Morphing.

  3. At the interface between the fluid film and the gas (on the gas side), configure the Morpher to allow Simcenter STAR-CCM+ internal models to add to the displacement.

    Under the Regions > [Fluid] > Boundaries > [Boundary Name] > Physics Conditions > Morpher node, set the Method to Internal.

  4. In the Solidified Film Removal Properties window, set the Smoothing Steps property to the appropriate value.

    This property affects the smoothing of the morphed surface that is used to model the surface of the solidified mass. At each iteration, the smoothing process is repeated the specified number of times.