U

The conditional density in the unburnt gases,

ρ_{u}

in Eqn. (3902).


Function Name:	`Unburnt Density`
Dimensions:	[Mass/Volume]
Default units:	kg/m^3
Type:	Scalar
Activated by:	Conditional Enthalpy model

The heat that is released due to kinetic activity in the unburnt gases. This field function allows you to visualize areas in which the unburnt heat release rates are high—which indicates that knock is more likely to occur.


Function Name:	`UnburntHeatReleaseRate`
Dimensions:	[Energy/Volume-Time]
Default units:	J/m³-s
Type:	Scalar
Activated by:	Turbulent Flame Speed Closure (Complex Chemistry)

α_{u}

in Eqn. (3445).


Function Name:	`UnburntThermalDiffusivity`
Dimensions:	[Length²/Time]
Default units:	m²/s
Type:	Scalar
Activated by:	Turbulent Flame Speed Closure (Complex Chemistry)

The conditional temperature in the unburnt gases. Allows you to construct the flame speed.


Function Name:	`UnburntTemperature`
Dimensions:	[Temperature]
Default units:	K
Type:	Scalar
Activated by:	Conditional Enthalpy model, ECFM-CLEH model, Turbulent Flame Speed Closure model

This field function displays any unclosed cells. A topologically closed volume cell consists of edges that are connected to exactly two faces, and faces with normals pointing outwards. If a cell is missing a face or the outward normals are not consistent, then it is considered unclosed and invalidates the mesh.


Function Name:	`Unmatched Edge Count`
Dimensions:	[Dimensionless]
Default units:	N/A
Type:	Scalar
Activated by:	Volume mesh models

y

in [eqnlink].


Function Name:	`UnnormalizedProgressVariableCFM`
Dimensions:	[Dimensionless]
Default units:	N/A
Type:	Scalar
Activated by:	Coherent Flame model, Turbulent Flame Speed Closure model

y_{var}

in Eqn. (3536).


Function Name:	`ScaledProgressVariableVariance`
Dimensions:	[Dimensionless]
Default units:	N/A
Type:	Scalar
Activated by:	Coherent Flame model, Turbulent Flame Speed Closure model

Volume-averaged density on the inflow plane for each bucket on the inflow plane mesh. For more information, see Inflow Velocity Plane.

This field function is specific to the User Defined Method of the Virtual Disk model. It is made available to access the flow field values to define the volumetric source term through field functions or user coding. You cannot visualize this field function on the volume mesh cells or on the virtual disk mesh points.


Function Name:	`UserInflowPlaneDensity<n>`
Dimensions:	[Mass/Volume]
Default units:	kg/m³
Type:	Scalar
Activated by:	Virtual Disk

Volume-averaged velocity on the inflow plane for each bucket on the inflow plane mesh. For more information, see Inflow Velocity Plane.

This field function is specific to the User Defined Method of the Virtual Disk model. It is made available to access the flow field values to define the volumetric source term through field functions or user coding. You cannot visualize this field function on the volume mesh cells or on the virtual disk mesh points.


Function Name:	`UserInflowPlaneVelocity<n>`
Dimensions:	[Velocity]
Default units:	m/s
Type:	Array
Activated by:	Virtual Disk

The user-defined value of diffuse radiation flux specified on a boundary. This flux models non-thermal (non-Planck) emission coming out of a boundary. It does not directly affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`DiffuseFlux`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Gray Thermal Radiation model, k-Distribution Thermal Radiation model

The user-defined value of directional radiation flux specified on the external side of a boundary. This flux models non-thermal (non-Planck) emission coming out of a boundary. It does not directly affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`[TBS]`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Gray Thermal Radiation

The user-defined value of directional radiation flux specified on the external side of a boundary. This flux models non-thermal (non-Planck) emission coming out of a boundary. It does not directly affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`[TBS]`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Gray Thermal Radiationrtfg

The user-defined value of spectral directional radiation flux specified on a boundary for <band-name>. This flux models non-thermal (non-Planck) emission in <band-name> coming out of a boundary. It does not affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`[TBS]`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Gray Thermal Radiation

The user-defined value of diffuse radiation flux for band <band-name> specified on a boundary. This flux models non-thermal (non-Planck) emission coming out of a boundary. It does not affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`SpectralDiffuseFlux<n>`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Multiband Thermal Radiation Model

The user-defined value of diffuse radiation flux specified on the external side of a boundary. This flux models non-thermal (non-Planck) emission coming out of a boundary. It does not directly affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`ExternalDiffuseFlux`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Gray Thermal Radiation model, k-Distribution Thermal Radiation model

The user-defined value of spectral diffuse radiation flux specified on a boundary for <band-name>. This flux models non-thermal (non-Planck) emission in <band-name> coming out of a boundary. It does not affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`ExternalSpectralDiffuseFlux<n>`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Multiband Thermal Radiation Model

The user-defined value of spectral directional radiation flux specified on a boundary for <band-name>. This flux models non-thermal (non-Planck) emission in <band-name> coming out of a boundary. It does not affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`SpectralDirectionalFlux<n>`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Multiband Thermal Radiation Model

The user-defined value of spectral directional radiation flux specified on the external side of a boundary for <band-name>. This flux models non-thermal (non-Planck) emission in <band-name> coming out of a boundary. It does not affect the originating boundary thermally but can affect other boundaries thermally.


Function Name:	`ExternalSpectralDirectionalFlux<n>`
Dimensions:	[Power/Length²]
Default units:	W/m²
Type:	Scalar
Activated by:	Multiband Thermal Radiation Model

The reference velocity

u^{*}

, computed according to the selected wall treatment.


Function Name:	`Ustar`
Dimensions:	[Velocity]
Default units:	m/s
Type:	Scalar
Activated by:	Wall Treatment models