VOF Waves Model Reference

VOF waves can be modeled in a single physics continuum only.

Table 1. VOF Waves Model Reference
Theory	See Free Surface Waves.
Provided By	[physics continuum] > Models > Optional Models
Example Node Path	Continua > Physics 1 > Models > VOF Waves
Requires	Space: Three Dimensional Material: Multiphase Multiphase Model: Volume of Fluid (VOF) Optional Models: VOF Waves
Properties	See VOF Waves Model Properties.
Specific Right-Click Actions	See Right-Click Actions.
Activates	Models	VOF Wave Zone Distance See VOF Wave Zone Distance Model Reference.
	Model Controls (child nodes)	Activates the Vorticity Limiter realizability option for the K-Omega and the Standard and Realizable K-Epsilon turbulence models. See K-Epsilon Realizability Option and K-Omega Realizability Option. Activates the Waves node. See VOF Wave Type Reference.
	Reference Values	Minimum Allowable Wall Distance See Reference Values.
	Region Inputs	See Region Settings.
	Boundary Inputs	See Boundary Settings.
	Field Functions	Damping Source Term, Forcing Source Term See Field Functions.

VOF Waves Model Properties

Damping Constant 1: Specifies $f_{1}$ in Eqn. (334), used in VOF wave damping.
Damping Constant 2: Specifies $f_{2}$ in Eqn. (334), used in VOF wave damping.
Damping Exponent: Specifies $n_{d}$ in Eqn. (335), used in VOF wave damping.

Note	It is possible to specify Damping Constant 1, Damping Constant 2, and Damping Exponent constants as parameters. See Global Parameters.

Enable Theory Comparison: When this option is activated, the VOF Waves field functions are also updated in the inner fluid domain. When this option is deactivated, the VOF Waves field functions are updated only on the boundaries of the fluid domain.
Hence, it is possible to plot the entire scalar field of the VOF Waves field functions. This plot shows the solution of Stokes wave theory of the selected wave with respective order. You can compare this theoretical solution to a plot of the volume fraction that is obtained through the solution of the transport equation.
Forcing Constant: Specifies the forcing coefficient, $γ$ in Eqn. (337), used in VOF wave forcing.

Right-Click Actions

The following right-click actions become available on the VOF Waves > Waves node.

New > [wave type]: where [wave type] is one of Flat, First Order, Fifth Order, Cnoidal, Superposition, Irregular, or Linked.

For information on each of the wave types, see Modeling VOF Waves and VOF Wave Type Reference.

Reference Values

Minimum Allowable Wall Distance: The wall distance algorithm has been developed to return a positive definite value for almost all cell shapes. However it is possible that some degenerate cells, such as boundary sliver cells, could return a value that is close to zero. Since turbulence models and wall functions require a non-zero value, this could cause numerical problems. For this reason, the minimum allowable wall distance limits the value of the wall distance in the continuum. The default value is 1.0E-6 m.
If the wall distance is limited in one or more cells, a warning message is displayed. In this case, investigate the cause and attempt to remedy the situation.

Region Settings

Applies to fluid regions.

VOF Wave Zone Option

Specifies the type of VOF wave treatment that is applied to the specified zone in the region.

Method	Corresponding Physics Value Nodes
None No damping or forcing is applied.	None
Damping Damping is activated. A Damping Length Specification node is added to the physics conditions for the region.	VOF Wave Damping Length The distance from the VOF wave damping-enabled boundary at which the damping starts. The specified value must be at least one wavelength. See Eqn. (335), the starting point for wave damping. According to Eqn. (334), there is a resistance term added to the equation for $w$ -velocity [121]. In order to be consistent with all effects, the effect of the damping is included in the wave profiles that are used for initialization.
Forcing Forcing is activated. A Forcing Length Specification node is added to the physics conditions for the region.	Forcing VOF Wave Specification This setting defines the VOF wave to which the simulation solution is forced at the boundary. This value is $ϕ^{*}$ in Eqn. (337). VOF Wave Select the appropriate wave from the list of VOF waves that are currently set up in the physics continuum. For simulations with more than one VOF wave, to simplify setting the region conditions for each wave, you can assign a Linked VOF Wave to the forcing VOF wave specification. VOF Wave Forcing Length See description below.
Forcing & Damping Both Forcing and Damping are activated. A Damping Length Specification node and a Forcing Length Specification node are added to the physics conditions for the region.	VOF Wave Damping Length See description above. Forcing VOF Wave Specification See description above. VOF Wave Forcing Length See description below.

Damping Length Specification

Specifies whether the damping length is set at the region level or set for individual boundaries. This setting is available when the VOF Wave Zone Option is set to Damping or Forcing & Damping.

Method	Corresponding Physics Value Nodes
Region The damping length is set at the region level.	VOF Wave Damping Length Specifies the distance from the VOF wave damping-enabled boundary at which the damping starts. The specified value must be at least one wavelength. The optimal damping zone length is around two wavelengths. You should make the solution domain longer than two wavelengths since the damping zone cannot start close to the body of interest.
Boundary The damping length is set for individual boundaries.	None. A VOF Wave Damping Length node is added to the physics values for each boundary in the region that has the VOF Wave Damping Boundary Option physics condition set to Yes.

Forcing Length Specification

Specifies whether the forcing length is set at the region level or set for individual boundaries. This setting is available when the VOF Wave Zone Option is set to Forcing or Forcing & Damping.

Method	Corresponding Physics Value Nodes
Region The forcing length is set at the region level.	VOF Wave Forcing Length Specifies the distance from the VOF wave forcing-enabled boundary at which the forcing starts. The specified value must be at least one wavelength. The optimal forcing zone length is around two wavelengths. You should make the solution domain longer than two wavelengths since the forcing zone cannot start close to the body of interest.
Boundary The forcing length is set for individual boundaries.	None. A VOF Wave Forcing Boundary Option node is added to the physics values for each boundary in the region that has the VOF Wave Forcing Boundary Option physics condition set to Yes.

Boundary Settings

VOF Wave Damping Boundary Option

This setting is available when the VOF Wave Zone Option in the physics conditions of the region is set to Damping or Forcing & Damping, and when the Damping Length Specification region condition is set to Boundary. It is available only in velocity inlet, pressure outlet, and symmetry boundaries.

Specifies whether VOF damping is used for the boundary.

Method	Corresponding Physics Value Nodes
No No damping is applied.	None
Yes Damping is applied in the damping zone before the boundary.	VOF Wave Damping Length The distance from the boundary at which the damping starts. The specified value must be at least one wavelength. The optimal damping zone length is around two wavelengths. You should make the solution domain longer than two wavelengths since the damping zone cannot start close to the body of interest.

VOF Wave Forcing Boundary Option

This setting is available when the VOF Wave Zone Option in the physics conditions of the region is set to Forcing or Forcing & Damping, and when the Forcing Length Specification region condition is set to Boundary. It is available only in velocity inlet, pressure outlet, and symmetry boundaries.

Specifies whether forcing to the specified VOF wave is used for the boundary.

Method	Corresponding Physics Value Nodes
No No forcing is applied.	None
Yes Forcing is applied in the forcing zone before the boundary.	VOF Wave Forcing Length The distance from the boundary at which the forcing starts. The specified value must be at least one wavelength. The optimal forcing zone length is around two wavelengths. You should make the solution domain longer than two wavelengths since the forcing zone cannot start close to the body of interest.

Field Functions

Damping Source Term: The damping source term is a resistance term that is added to the equation for $w$ -velocity. This value is $S_{z}^{d}$ in Eqn. (334).
Forcing Source Term: The wave forcing source term is added to the transport (momentum) equations. This value is $q_{ϕ}$ in Eqn. (337).