User Potential Force Model Reference

The User-Defined Potential Force models a potential $Φ$ that applies to a Eulerian phase for a particular physical application. Different physical applications have different potential forces: capillary pressure and osmotic pressure are two examples of this force.

The User Potential Force model is a general model and is intended for use with open regions (such as for foams and settling emulsions) and with porous regions (such as capillary pressure models in oil reservoirs).

Example applications where you can use this model are the imbibition of wetting liquids into porous media, foam drainage, and the flow of dense emulsions and suspensions.

Table 1. User Potential Force Model Reference
Provided By	[phase] > Models > Optional Models
Example Node Path	[phase] > Models > User Potential Force
Requires	Physics continuum selections: Material: Multiphase Multiphase Model: Eulerian Multiphase (EMP) (Automatically activates: Multiphase Interaction, Gradients) Eulerian phase selections: Material: any. Optional Models: User Potential Force
Properties	None.
Activates	Physics Models	None.
	Model Controls (child nodes)	User Potential See User Potential Properties. User Potential Force Prefactor See User Potential Force Prefactor Properties. User Potential Volume Fraction Derivative See User Potential Volume Fraction Derivative Properties.
	Field Functions	None.

User Potential Properties

The User Potential specifies the potential $Φ$ in Eqn. (2037). The potential can be a function of the volume fraction $α$ and/or other scalars.

Method: The User Potential profile can be specified as a field function, a table, or with user code.

User Potential Force Prefactor Properties

The User Potential Force Prefactor specifies the potential force prefactor $κ$ in Eqn. (2037). The potential force prefactor can be a function of the volume fraction $α$ and/or other scalars.

Method: The User Potential Force Prefactor profile can be specified as a constant, a field function, a table, or with user code.

User Potential Volume Fraction Derivative Properties

The User Potential Volume Fraction Derivative specifies an approximation for the derivative of the potential with respect to the volume fraction of the phase (Eqn. (2038)).

This value is used for linearization only so there is no requirement for an exact expression. Excessive linearization can slow down the convergence rate, so you are recommended to use the default value $\frac{\partial Φ}{\partial α} = 0$ . However, if the driving force is strong compared to other forces, it can lead to checker-boarding and instability. In these cases, the linearization stabilizes the calculations.

Method: The User Potential Volume Fraction Derivative profile can be specified as a constant, a field function, a table, or with user code.