The Phase Field in Fluids (pf) interface (
), found under the
Mathematics>Moving Interface branch (
) when adding a physics interface, is used to track moving fluid-fluid interfaces by solving two transport equations, one for the phase field variable,
ϕ, and one for the mixing energy density,
ψ. The position of the interface is determined by minimizing the free energy.
The main node is the Phase Field Model feature, which adds the phase field equations and provides an interface for defining the phase field model properties.
When this physics interface is added, the following default nodes are also added in the Model Builder —
Phase Field Model,
Wetted Wall (the default boundary condition),
Initial Values, and
Initial Values, Fluid 2. Then, from the
Physics toolbar, add other nodes that implement, for example, boundary conditions. You can also right-click
Phase Field in Fluids to select physics features from the context menu.
The Label is the default physics interface name.
The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern
<name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the
name string must be unique. Only letters, numbers, and underscores (
_) are permitted in the
Name field. The first character must be a letter.
The default Name (for the first physics interface in the model) is
pf.
This interface defines the dependent variables (fields) Phase field variable ϕ and
Phase field help variable ψ. If required, edit the name, but dependent variables must be unique within a model.
) and select 
