Phase Field Model

The Phase Field Model feature adds the applicable equations described in The Equations for the Phase Field Method and enables the definition of the associated phase field parameters.

D O M A I N S E L E C T I O N

From the Selection list, choose the domains to use the properties for the interface.

P H A S E F I E L D P A R A M E T E R S

Define the following phase field parameters. Enter a value or expression for the:

•Surface tension coefficient (SI unit: N/m).

•Parameter controlling interface thickness epf (SI unit: m). The default expression is pf.hmax/2, which means that the value is half of the maximum mesh element size

in the region where the interface passes.

•Mobility tuning parameter (SI unit: m·s/kg). The default is 1, which is a good starting point for most models. This parameter determines the time scale of the

Cahn-Hilliard diffusion and therefore also governs the diffusion-related time scale of the interface. Keep the parameter value large enough to maintain a constant

interface thickness but still low enough to not damp the convective motion. A too high mobility can also lead to excessive diffusion of droplets.

E X T E R N A L F R E E E N E R G Y

Add a source of external free energy to the phase field equations. This modifies the last term on the right side of the equation:

The external free energy f is a user defined free energy (SI unit: J/m3). In most cases, the external free energy is zero. Manually differentiate the expression for the external free energy with respect to and then enter it into the -derivative of external free energy field for f .

• Additional Sources of Free Energy

See Also

T H E P H A S E F I E L D I N T E R F A C E | 225