
Abs (CH) Spanwise Coordinate
(in the
Mesh... category) is the dimensional coordinate in the spanwise direction, from casing to hub. Its unit quantity is
length.

Abs (HC) Spanwise Coordinate
(in the
Mesh... category) is the dimensional coordinate in the spanwise direction, from hub to casing. Its unit quantity is
length.

Abs Meridional Coordinate
(in the
Mesh... category) is the dimensional coordinate that follows the flow path from inlet to outlet. Its unit quantity is
length.

Abs Pitchwise Coordinate
(in the
Mesh... category) is the dimensional coordinate in the circumferential (pitchwise) direction. Its unit quantity is
angle.

Absolute Pressure
(in the
Pressure... category) is equal to the operating pressure plus the gauge pressure. See Section
8.14 for details. Its unit quantity is
pressure.

Absorbed Radiation Flux (Bandn)
(in the
Wall Fluxes... category) is the amount of radiative heat flux absorbed by a semitransparent wall for a particular band of radiation. Its unit quantity is
heatflux.

Absorbed Visible Solar Flux, Absorbed IR Solar Flux
(in the
Wall Fluxes... category) is the amount of solar heat flux absorbed by a semitransparent wall for a visible or infrared (IR) radiation.

Absorption Coefficient
(in the
Radiation... category) is the property of a medium that describes the amount of absorption of thermal radiation per unit path length within the medium. It can be interpreted as the inverse of the mean free path that a photon will travel before being absorbed (if the absorption coefficient does not vary along the path). The unit quantity for
Absorption Coefficient is
lengthinverse.

Acentric Factor
(in the
Properties... category) is the mixture acentric factor. This property is available when a composition dependent option is selected for acentric factor in the cases with AungierRedlichKwong real gas model and species transport.

Acoustic Power
(in the
Acoustics... category) is the acoustic power per unit volume generated by isotropic turbulence (see
this equation in the separate
Theory Guide). It is available only when the
Broadband Noise Sources acoustics model is being used. Its unit quantity is
power per
volume.

Acoustic Power Level (dB)
(in the
Acoustics... category) is the acoustic power per unit volume generated by isotropic turbulence and reported in dB (see
this equation in the separate
Theory Guide). It is available only when the
Broadband Noise Sources acoustics model is being used.

Active Cell Partition
(in the
Cell Info... category) is an integer identifier designating the partition to which a particular cell belongs. In problems in which the mesh is divided into multiple partitions to be solved on multiple processors using the parallel version of
ANSYS FLUENT, the partition ID can be used to determine the extent of the various groups of cells. The active cell partition is used for the current calculation, while the stored cell partition (the last partition performed) is used when you save a case file. See Section
32.5.4 for more information.

Adaption...
includes field variables that are commonly used for adapting the mesh. For information about solution adaption, see Chapter
27.

Adaption Function
(in the
Adaption... category) can be either the
Adaption Space Gradient or the
Adaption Curvature, depending on the settings in the
Gradient Adaption dialog box. For instance, the
Adaption Curvature is the undivided Laplacian of the values in temporary cell storage. To display contours of the Laplacian of pressure, for example, you first select
Static Pressure, click the
Compute (or
Display) button, select
Adaption Function, and finally click the
Display button.

Adaption IsoValue
(in the
Adaption... category) is the desired field variable function.

Adaption Space Gradient
(in the
Adaption... category) is the first derivative of the desired field variable.

(31.41) 
Depending on the settings in the
Gradient Adaption dialog box, this equation will either be scaled or normalized. Recommended for problems with shock waves (i.e., supersonic, inviscid flows). For more information, see
this section in the separate
Theory Guide.

Adaption Curvature
(in the
Adaption... category) is the second derivative of the desired field variable.

(31.42) 
Depending on the settings in the
Gradient Adaption dialog box, this equation will either be scaled or normalized. Recommended for smooth solutions (i.e., viscous, incompressible flows). For more information, see
this section in the separate
Theory Guide.

Adiabatic Flame Temperature
(in the
Premixed Combustion... category) is the adiabatic temperature of burnt products in a laminar premixed flame (
in
this equation in the separate
Theory Guide). Its unit quantity is
temperature.

Angular Coordinate
(in the
Mesh... category) is the angle between the radial vector and the position vector. The radial vector is obtained by transforming the default radial vector (yaxis) by the same rotation that was applied to the default axial vector (zaxis ). This assumes that, after the transformation, the default axial vector (zaxis) becomes the reference axis. The angle is positive in the direction of crossproduct between reference axis and radial vector.

Abs. Angular Coordinate
(in the
Mesh... category) is the absolute value of the
Angular Coordinate defined above.

Axial Coordinate
(in the
Mesh... category) is the distance from the origin in the axial direction. The axis origin and (in 3D) direction is defined for each cell zone in the
Fluid or
Solid dialog box. The axial direction for a 2D model is always the
direction, and the axial direction for a 2D axisymmetric model is always the
direction. The unit quantity for
Axial Coordinate is
length.

Axial Pull Velocity
(in the
Solidification/Melting... category) is the axialdirection component of the pull velocity for the solid material in a continuous casting process. Its unit quantity is
velocity.

Axial Velocity
(in the
Velocity... category) is the component of velocity in the axial direction. (See Section
31.2 for details.) For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list. Its unit quantity is
velocity.

AxialWall Shear Stress
(in the
Wall Fluxes... category) is the axial component of the force acting tangential to the surface due to friction. Its unit quantity is
pressure.

Beam Irradiation Flux (Bandb)
(in the
Wall Fluxes... category) is specified as an incident heat flux (
) for each wavelength band.

Boundary Cell Distance
(in the
Adaption... category) is an integer that indicates the approximate number of cells from a boundary zone.

Boundary Normal Distance
(in the
Adaption... category) is the distance of the cell centroid from the closest boundary zone.

Boundary Volume Distance
(in the
Adaption... category) is the cell volume distribution based on the
Boundary Volume,
Growth Factor, and normal distance from the selected
Boundary Zones defined in the
Boundary Adaption dialog box. See Section
27.2 for details.

Cell Children
(in the
Adaption... category) is a binary identifier based on whether a cell is the product of a cell subdivision in the hangingnode adaption process (value = 1) or not (value = 0).

Cell Element Type
(in the
Cell Info... category) is the integer cell element type identification number. Each cell can have one of the following element types:
triangle 1
tetrahedron 2
quadrilateral 3
hexahedron 4
pyramid 5
wedge 6


Cell Equiangle Skew
(in the
Mesh... category) is a nondimensional parameter calculated using the normalized angle deviation method, and is defined as

(31.43) 
where

= 
largest angle in the face or cell 

= 
smallest angle in the face or cell 

= 
angle for an equiangular face or cell 


(e.g., 60 for a triangle and 90 for a square) 
A value of 0 indicates a best case equiangular cell, and a value of 1 indicates a completely degenerate cell. Degenerate cells (slivers) are characterized by nodes that are nearly coplanar (collinear in 2D).
Cell Equiangle Skew applies to all elements.

Cell Equivolume Skew
(in the
Mesh... category) is a nondimensional parameter calculated using the volume deviation method, and is defined as

(31.44) 
where optimalcellsize is the size of an equilateral cell with the same circumradius. A value of 0 indicates a best case equilateral cell and a value of 1 indicates a completely degenerate cell. Degenerate cells (slivers) are characterized by nodes that are nearly coplanar (collinear in 2D).
Cell Equivolume Skew applies only to triangular and tetrahedral elements.

Cell Id
(in the
Cell Info... category) is a unique integer identifier associated with each cell.

Cell Info...
includes quantities that identify the cell and its relationship to other cells.

Cell Partition
(in the
Cell Info... category) is an integer identifier designating the partition to which a particular cell belongs. In problems in which the mesh is divided into multiple partitions to be solved on multiple processors using the parallel version of
ANSYS FLUENT, the partition ID can be used to determine the extent of the various groups of cells.

Cell Refine Level
(in the
Adaption... category) is an integer that indicates the number of times a cell has been subdivided in the hanging node adaption process, compared with the original mesh. For example, if one quad cell is split into four quads, the
Cell Refine Level for each of the four new quads will be 1. If the resulting four quads are split again, the
Cell Refine Level for each of the resulting 16 quads will be 2.

Cell Reynolds Number
(in the
Velocity... category) is the value of the Reynolds number in a cell. (Reynolds number is a dimensionless parameter that is the ratio of inertia forces to viscous forces.)
Cell Reynolds Number is defined as

(31.45) 
where
is density,
is velocity magnitude,
is the effective viscosity (laminar plus turbulent), and
is
Cell Volume
for 2D cases and
Cell Volume
in 3D or axisymmetric cases.

Cell Squish Index
(in the
Mesh... category) is a measure of the quality of a mesh, and is calculated from the dot products of each vector pointing from the centroid of a cell toward the center of each of its faces, and the corresponding face area vector as

(31.46) 
Therefore, the worst cells will have a
Cell Squish Index close to 1.

Cell Surface Area
(in the
Adaption... category) is the total surface area of the cell, and is computed by summing the area of the faces that compose the cell.

Cell Volume
(in the
Mesh... category) is the volume of a cell. In 2D the volume is the area of the cell multiplied by the unit depth. For axisymmetric cases, the cell volume is calculated using a reference depth of 1 radian. The unit quantity of
Cell Volume is
volume.
Cell Volume Derivative
(in the
Mesh... category) is the change of a cell volume over time.
Cell Volume Error
(in the
Mesh... category) is the cell volume over the unsteady cell volume.

2D Cell Volume
(in the
Mesh... category) is the twodimensional volume of a cell in an axisymmetric computation. For an axisymmetric computation, the 2D cell volume is scaled by the radius. Its unit quantity is
area.

Cell Volume Change
(in the
Adaption... category) is the maximum volume ratio of the current cell and its neighbors.

Cell Wall Distance
(in the
Mesh... category) is the distribution of the normal distance of each cell centroid from the wall boundaries. Its unit quantity is
length.

Cell Warpage
(in the
Adaption... category) is the square root of the ratio of the distance between the cell centroid and cell circumcenter and the circumcenter radius:

(31.47) 

Cell Zone Index
(in the
Cell Info... category) is the integer cell zone identification number. In problems that have more than one cell zone, the cell zone ID can be used to identify the various groups of cells.

Cell Zone Type
(in the
Cell Info... category) is the integer cell zone type ID. A fluid cell has a type ID of 1, a solid cell has a type ID of 17, and an exterior cell (parallel solver) has a type ID of 21.

Compressibility Factor
(in the
Properties... category) is the ratio of the ideal gas density of the fluid divided by the real gas fluid density in the in the same flow conditions. Compressibility Factor is defined as

(31.48) 
where
is the compressibility factor,
is the absolute pressure,
is the temperature, and
(the universal gas constant
divided by the molecular weight
). The compressibility factor is available only with the real gas models.

Contact Resistivity
(in the
Solidification/Melting... category) is the additional resistance at the wall due to contact resistance. It is equal to
, where
is the contact resistance,
is the liquid fraction, and
is the cell height of the walladjacent cell. The unit quantity for
Contact Resistivity is
thermalresistivity.

Critical Pressure
(in the
Properties... category) is the mixture critical pressure. This property is available when a composition dependent option is selected for critical pressure in the cases with AungierRedlichKwong real gas model and species transport.

Critical Specific Volume
(in the
Properties... category) is the mixture critical specific volume. This property is available when a composition dependent option is selected for critical specific volume in the cases with AungierRedlichKwong real gas model and species transport.

Critical Strain Rate
(in the
Premixed Combustion... category) is a parameter that takes into account the stretching and extinction of premixed flames (
in
this equation in the separate
Theory Guide). Its unit quantity is
timeinverse.

Critical Temperature
(in the
Properties... category) is the mixture critical temperature. This property is available when a composition dependent option is selected for critical temperature in the cases with AungierRedlichKwong real gas model and species transport

Custom Field Functions...
are scalar field functions defined by you. You can create a custom function using the
Custom Field Function Calculator dialog box. All defined custom field functions will be listed in the lower dropdown list. See Section
31.5 for details.

Damkohler Number
(in the
Premixed Combustion... category) is a nondimensional parameter that is defined as the ratio of turbulent to chemical time scales.

Density...
includes variables related to density.

Density
(in the
Density... category) is the mass per unit volume of the fluid. Plots or reports of
Density include only fluid cell zones. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list. The unit quantity for
Density is
density.

Density All
(in the
Density... category) is the mass per unit volume of the fluid or solid material. Plots or reports of
Density All include both fluid and solid cell zones. The unit quantity for
Density All is
density.

Derivatives...
are the viscous derivatives. For example,
dXVelocity/dx is the first derivative of the
component of velocity with respect to the
coordinate direction. You can compute first derivatives of velocity, angular velocity, and pressure in the pressurebased solver, and first derivatives of velocity, angular velocity, temperature, and species in the densitybased solvers.

Diameter
(in the
Properties... category) is the diameter of particles, droplets, or bubbles of the secondary phase selected in the
Phase dropdown list. Its unit quantity is
length.

Diffusion Coef. of Scalarn
(in the
User Defined Scalars... category) is the diffusion coefficient for the
th userdefined scalar transport equation. See the separate UDF manual for details about defining userdefined scalars.

Discrete Phase Model...
includes quantities related to the discrete phase model. See Chapter
23 for details about this model.

DPM Absorption Coefficient
(in the
Discrete Phase Model... category) is the absorption coefficient for discretephase calculations that involve radiation (
in
this equation in the separate
Theory Guide). Its unit quantity is
lengthinverse.

DPM Accretion
(in the
Discrete Phase Model... category) is the accretion rate calculated at a wall boundary:

(31.49) 
where
is the mass flow rate of the particle stream, and
is the area of the wall face where the particle strikes the boundary. This item will appear only if the optional erosion/accretion model is enabled. See Section
23.2.5 for details. The unit quantity for
DPM Accretion is
massflux.

DPM Burnout
(in the
Discrete Phase Model... category) is the exchange of mass from the discrete to the continuous phase for the combustion law (Law 5) and is proportional to the solid phase reaction rate. The burnout exchange has units of
massflow.

DPM Concentration
(in the
Discrete Phase Model... category) is the total concentration of the discrete phase. Its unit quantity is
density.

DPM Emission
(in the
Discrete Phase Model... category) is the amount of radiation emitted by a discretephase particle per unit volume. Its unit quantity is
heatgenerationrate.

DPM Enthalpy Source
(in the
Discrete Phase Model... category) is the exchange of enthalpy (sensible enthalpy plus heat of formation) from the discrete phase to the continuous phase. The exchange is positive when the particles are a source of heat in the continuous phase. The unit quantity for
DPM Enthalpy Source is
power.

DPM Erosion
(in the
Discrete Phase Model... category) is the erosion rate calculated at a wall boundary face:

(31.410) 
where
is the mass flow rate of the particle stream,
is the impact angle of the particle path with the wall face,
is the function specified in the
Wall dialog box, and
is the area of the wall face where the particle strikes the boundary. This item will appear only if the optional erosion/accretion model is enabled. See Section
23.2.5 for details. The unit quantity for
DPM Erosion is
massflux.

DPM Evaporation/Devolatilization
(in the
Discrete Phase Model... category) is the exchange of mass, due to dropletparticle evaporation or combustingparticle devolatilization, from the discrete phase to the evaporating or devolatilizing species. If you are not using the nonpremixed combustion model, the mass source for each individual species (
DPM speciesn Source, below) is also available; for nonpremixed combustion, only this sum is available. The unit quantity for
DPM Evaporation/Devolatilization is
massflow.

DPM Mass Source
(in the
Discrete Phase Model... category) is the total exchange of mass from the discrete phase to the continuous phase. The mass exchange is positive when the particles are a source of mass in the continuous phase. If you are not using the nonpremixed combustion model,
DPM Mass Source will be equal to the sum of all species mass sources (
DPM speciesn Source, below); if you are using the nonpremixed combustion model, it will be equal to
DPM Burnout plus
DPM Evaporation/Devolatilization. The unit quantity for
DPM Mass Source is
massflow.

DPM Scattering
(in the
Discrete Phase Model... category) is the scattering coefficient for discretephase calculations that involve radiation (
in
this equation in the separate
Theory Guide). Its unit quantity is
lengthinverse.

DPM Sensible Enthalpy Source
(in the
Discrete Phase Model... category) is the exchange of sensible enthalpy from the discrete phase to the continuous phase. The exchange is positive when the particles are a source of heat in the continuous phase. Its unit quantity is
power.

DPM speciesn Source
(in the
Discrete Phase Model... category) is the exchange of mass, due to dropletparticle evaporation or combustingparticle devolatilization, from the discrete phase to the evaporating or devolatilizing species. (The name of the species will replace
speciesn in
DPM speciesn Source.) These species are specified in the
Set Injection Properties dialog box, as described in Section
23.3.15. The unit quantity is
massflow. Note that this variable will not be available if you are using the nonpremixed combustion model; use
DPM Evaporation/Devolatilization instead.

DPM Swirl Momentum Source
(in the
Discrete Phase Model... category) is the exchange of swirl momentum from the discrete phase to the continuous phase. This value is positive when the particles are a source of momentum in the continuous phase. The unit quantity is
force.

DPM X, Y, Z Momentum Source
(in the
Discrete Phase Model... category) are the exchange of
,
, and
direction momentum from the discrete phase to the continuous phase. These values are positive when the particles are a source of momentum in the continuous phase. The unit quantity is
force.
Dynamic Cell Volume Change
(in the
Mesh... category) is the change of a cell volume.

Dynamic Pressure
(in the
Pressure... category) is defined as
. Its unit quantity is
pressure.

Eff Diff Coef of speciesn
(in the
Species... category) is the sum of the laminar
and turbulent diffusion coefficients of a species into the mixture:
(The name of the species will replace
speciesn in
Eff Diff Coef of speciesn.) The unit quantity is
massdiffusivity.

Effective Prandtl Number
(in the
Turbulence... category) is the ratio
, where
is the effective viscosity,
is the specific heat, and
is the effective thermal conductivity.

Effective Thermal Conductivity
(in the
Properties... category) is the sum of the laminar and turbulent thermal conductivities,
, of the fluid. A large thermal conductivity is associated with a good heat conductor and a small thermal conductivity with a poor heat conductor (good insulator). Its unit quantity is
thermalconductivity.

Effective Viscosity
(in the
Turbulence... category) is the sum of the laminar and turbulent viscosities of the fluid. Viscosity,
, is defined by the ratio of shear stress to the rate of shear. Its unit quantity is
viscosity.

Enthalpy
(in the
Temperature... category) is defined differently for compressible and incompressible flows, and depending on the solver and models in use.
For compressible flows,

(31.411) 
and for incompressible flows,

(31.412) 
where
and
are, respectively, the mass fraction and enthalpy of species
. (See
Enthalpy of speciesn, below). For the pressurebased solver, the second term on the righthand side of Equation
31.412 is included only if the pressure work term is included in the energy equation (see
this section in the separate
Theory Guide). For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list. For all reacting flow models, the
Enthalpy plots consist of the thermal (or sensible) plus chemical energy. The unit quantity for
Enthalpy is
specificenergy.
In the case of the inert model (
this section in the separate
Theory Guide), the enthalpy in a cell is split into the contributions from the inert and the reacting fractions of the gas phase species in the cell. The cell enthalpy is partitioned as

(31.413) 
where
is the fraction of inert species in the cell. The quantity
is the enthalpy of the inert species at the cell temperature, similarly
is the enthalpy of the active species at the cell temperature. It is assumed that the cell temperature is common to both inert and active species, so
,
and the cell temperature are chosen so that Equation
31.413 is satisfied.

Enthalpy of speciesn
(in the
Species... category) is defined differently depending on the solver and models options in use. The quantity:

(31.414) 
where
is the formation enthalpy of species
at the reference temperature
, is reported only for nonadiabatic PDF cases, or if the densitybased solver is selected. The quantity:

(31.415) 
where
, is reported in all other cases. The unit quantity for
Enthalpy of speciesn is
specificenergy.

Entropy
(in the
Temperature... category) is a thermodynamic property defined by the equation

(31.416) 
where "rev'' indicates an integration along a reversible path connecting two states,
is heat, and
is temperature. For compressible flows, entropy is computed using the equation

(31.417) 
where the reference temperature
and reference pressure
are defined in the
Reference Values dialog box. For incompressible flow, the entropy is computed using the equation

(31.418) 
where
is the specific heat at constant pressure. The unit quantity for entropy is
specificheat.


Note that for the real gas models the entropy is computed accordingly by the appropriate equation of state formulation.


Existing Value
(in the
Adaption... category) is the value that presently resides in the temporary space reserved for cell variables (i.e., the last value that you displayed or computed).

Face Area Magnitude
(in the
Mesh... category) is the magnitude of the face area vector for noninternal faces (i.e., faces that only have
c0 and no
c1). The values are stored on the face itself and used when required. This variable is intended only for zone surfaces and not for other surfaces created for postprocessing.

Face Handedness
(in the
Mesh... category) is a parameter that is equal to one in cells that are adjacent to lefthanded faces, and zero elsewhere. It can be used to locate mesh problems.

Face Squish Index
(in the
Mesh... category) is a measure of the quality of a mesh, and is calculated from the dot products of each face area vector, and the vector that connects the centroids of the two adjacent cells as

(31.419) 
Therefore, the worst cells will have a
Face Squish Index close to 1.

Fine Scale Mass Fraction of speciesn
(in the
Species... category) is the term
in
this equation in the separate
Theory Guide.

Fine Scale Temperature
(in the
Temperature... category) is the temperature of the fine scales, which is calculated from the enthalpy when the reaction proceeds over the time scale (
in
this equation in the separate
Theory Guide), governed by the Kinetic rates of
this equation in the separate
Theory Guide. Its unit quantity is
temperature.

Fine Scale Transfer Rate
(in the
Species... category) is the transfer rate of the fine scales, which is equal to the inverse of the time scale (
in
this equation in the separate
Theory Guide). Its unit quantity is
timeinverse.

1Fine Scale Volume Fraction
(in the
Species... category) is a function of the fine scale volume fraction (
in
this equation in the separate
Theory Guide). The quantity is subtracted from unity to make it easier to interpret.

Fvar Prod
(in the
Pdf... category) is the production term in the mixture fraction variance equation solved in the nonpremixed combustion model (i.e., the last two terms in
this equation in the separate
Theory Guide).

Fvar2 Prod
(in the
Pdf... category) is the production term in the secondary mixture fraction variance equation solved in the nonpremixed combustion model. See
this equation in the separate
Theory Guide.

Gas Constant (R)
(in the
Properties... category) is the gas constant of the fluid. Its unit quantity is
specificheat.

Granular Conductivity
(in the
Properties... category) is equivalent to the diffusion coefficient in
this equation in the separate
Theory Guide. For more information, see
this section in the separate
Theory Guide. Its unit quantity is kg/ms.

Granular Pressure...
includes quantities for reporting the solids pressure for each granular phase (
in
this equation in the separate
Theory Guide). See
this section in the separate
Theory Guide for details. Its unit quantity is
pressure. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Granular Temperature...
includes quantities for reporting the granular temperature for each granular phase (
in
this equation in the separate
Theory Guide). See
this section in the separate
Theory Guide for details. Its unit quantity is
. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Mesh...
includes variables related to the mesh.

Mesh XVelocity, Mesh YVelocity, Mesh ZVelocity
(in the
Velocity... category) are the vector components of the mesh velocity for movingmesh problems (rotating or multiple reference frames, mixing planes, or sliding meshes). Its unit quantity is
velocity.

HCN Density
(in the
NOx... category) is the mass per unit volume of HCN. The unit quantity is
density. The
HCN Density will appear only if you are modeling fuel NOx. See
this section in the separate
Theory Guide for details.

Heat of Heterogeneous Reaction
(in the
Phase Interaction... category) is the heat added or removed due to heterogeneous chemical reactions. For exothermic reactions the
Heat of Heterogeneous Reaction is reported as a positive quantity, while for endothermic reactions it will be a negative quantity. If you have more than one heterogeneous reaction defined in your case, the
Heat of Heterogeneous Reaction reported is the sum of the heat for all heterogeneous reactions. The unit quantity of
Heat of Heterogeneous Reaction is Watt.

Heat of Reaction
(in the
Reactions... category) is the heat added or removed due to chemical reactions, as defined in
this equation in the separate
Theory Guide. For exothermic reactions, the heat of reaction is reported as a positive quantity, while for endothermic reactions it is reported as a negative quantity. If you have more than one reaction defined in your case, the
Heat of Reaction reported is the sum of the heat for all reactions. The unit of measurement for the heat of reaction is Watts. The
Heat of Reaction is not available for the nonpremixed and partiallypremixed models.

Helicity
(in the
Velocity... category) is defined by the dot product of vorticity and the velocity vector.

(31.420) 
It provides insight into the vorticity aligned with the fluid stream. Vorticity
is a measure of the rotation of a fluid element as it moves in the flow field.

Incident Radiation
(in the
Radiation... category) is the total radiation energy,
, that arrives at a location per unit time and per unit area:

(31.421) 
where
is the radiation intensity and
is the solid angle.
is the quantity that the P1 radiation model computes. For the DO radiation model, the incident radiation is computed over a finite number of discrete solid angles, each associated with a vector direction. The unit quantity for
Incident Radiation is
heatflux.

Incident Radiation (Band n)
(in the
Radiation... category) is the radiation energy contained in the wavelength band
for the nongray DO radiation model. Its unit quantity is
heatflux.

Intermittency Factor (
)
(in the
Turbulence... category) is a measure of the probability that a given point is located inside a turbulent region. Upstream of transition the intermittency is zero. Once the transition occurs, the intermittency is ramped up to one until the fully turbulent boundary layer regime is achieved.

Internal Energy
(in the
Temperature... category) is the summation of the kinetic and potential energies of the molecules of the substance per unit volume (and excludes chemical and nuclear energies).
Internal Energy is defined as
. Its unit quantity is
specificenergy.

Jet Acoustic Power
(in the
Acoustics... category) is the acoustic power for turbulent axisymmetric jets (see
this equation in the separate
Theory Guide). It is available only when the
Broadband Noise Sources acoustics model is being used.

Jet Acoustic Power Level (dB)
(in the
Acoustics... category) is the acoustic power for turbulent axisymmetric jets, reported in dB (see
this equation in the separate
Theory Guide). It is available only when the
Broadband Noise Sources acoustics model is being used.

Kinetic Rate of Reactionn
(in the
Reactions... category) is given by the following expression (see
this equation in the separate
Theory Guide for definitions of the variables shown here):
The reported value is independent of any particular species, and has units of kgmol/m
s.
To find the rate of production/destruction for a given species
due to reaction
, multiply the reported reaction rate for reaction
by the term
, where
is the molecular weight of species
, and
and
are the stoichiometric coefficients of species
in reaction
.
For particle reactions it is the global rate of the particle reaction n expressed in kmol/s/m3. This is computed as
where
is the rate of particle species depletion (or generation) given by
this equation in the separate
Theory Guide ,
is the particle species molecular weight, and
is the cell volume.

Lam Diff Coef of speciesn
(in the
Species... category) is the laminar diffusion coefficient of a species into the mixture,
. Its unit quantity is
massdiffusivity.

Laminar Flame Speed
(in the
Premixed Combustion... category) is the propagation speed of laminar premixed flames (
in
this equation in the separate
Theory Guide). Its unit quantity is
velocity.

Laminar Kinetic Energy (kl)
(in the
Turbulence...category) is a measure of the "laminar'' streamwise fluctuations present in the pretransitional region of the boundary layer subjected to freestream turbulence. A transport equation of kl is considered by the kklomega transition model.

LEE SelfNoise XSource, LEE SelfNoise YSource, LEE SelfNoise ZSource
(in the
Acoustics... category ) are the selfnoise source terms in the linearized Euler equation for the acoustic velocity component (see
this equation in the separate
Theory Guide). They are available only when the
Broadband Noise Sources acoustics model is being used.

LEE ShearNoise XSource, LEE ShearNoise YSource, LEE ShearNoise ZSource
(in the
Acoustics... category ) are the shearnoise source terms in the linearized Euler equation for the acoustic velocity component (see
this equation in the separate
Theory Guide). They are available only when the
Broadband Noise Sources acoustics model is being used.

LEE Total Noise XSource, LEE Total Noise YSource, LEE Total Noise ZSource
(in the
Acoustics... category ) are the total noise source terms in the linearized Euler equation for the acoustic velocity component (see
this equation in the separate
Theory Guide). The total noise source term is the sum of the selfnoise and shearnoise source terms. They are available only when the
Broadband Noise Sources acoustics model is being used.

Lilley's SelfNoise Source
(in the
Acoustics... category ) is the selfnoise source term in the linearized Lilley's equation (see
this equation in the separate
Theory Guide), available only when the
Broadband Noise Sources acoustics model is being used.

Lilley's ShearNoise Source
(in the
Acoustics... category ) is the shearnoise source term in the linearized Lilley's equation (see
this equation in the separate
Theory Guide), available only when the
Broadband Noise Sources acoustics model is being used.

Lilley's Total Noise Source
(in the
Acoustics... category ) is the total noise source term in the linearized Lilley's equation (see
this equation in the separate
Theory Guide). The total noise source term is the sum of the selfnoise and shearnoise source terms, available only when the
Broadband Noise Sources acoustics model is being used.

Liquid Fraction
(in the
Solidification/Melting... category) is the liquid fraction
computed by the solidification/melting model:

(31.422) 

Mach Number
(in the
Velocity... category) is the ratio of velocity and speed of sound.

Mass fraction of HCN, Mass fraction of NH3, Mass fraction of NO, Mass fraction of N2O
(in the
NOx... category) are the mass of HCN, the mass of NH
, the mass of NO, and the mass of N
O per unit mass of the mixture (e.g., kg of HCN in 1 kg of the mixture). The
Mass fraction of HCN and the
Mass fraction of NH3 will appear only if you are modeling fuel NOx. See
this section in the separate
Theory Guide for details.

Mass fraction of nuclei
(in the
Soot... category) is the number of particles per unit mass of the mixture (in units of particles
/kg) The
Mass fraction of nuclei will appear only if you use the twostep soot model. See Section
21.3 for details.

Mass fraction of soot
(in the
Soot... category) is the mass of soot per unit mass of the mixture (e.g., kg of soot in 1 kg of the mixture). See Section
21.3 for details.

Mass fraction of speciesn
(in the
Species... category) is the mass of a species per unit mass of the mixture (e.g., kg of species in 1 kg of the mixture).

Mean quantityn
(in the
Unsteady Statistics... category) is the timeaveraged value of a solution variable (e.g.,
Static Pressure). See Section
26.12.4 for details.

Meridional Coordinate
(in the
Mesh... category) is the normalized (dimensionless) coordinate that follows the flow path from inlet to outlet. Its value varies from
to
.

Mixture Fraction Variance
(in the
Pdf... category) is the variance of the mixture fraction solved for in the nonpremixed combustion model. This is the second conservation equation (along with the mixture fraction equation) that the nonpremixed combustion model solves. (See
this section in the separate
Theory Guide.)

Modified Turbulent Viscosity
(in the
Turbulence... category) is the transported quantity
that is solved for in the SpalartAllmaras turbulence model (see
this equation in the separate
Theory Guide). The turbulent viscosity,
, is computed directly from this quantity using the relationship given by
this equation in the separate
Theory Guide. Its unit quantity is
viscosity.

Molar Concentration of speciesn
(in the
Species... category) is the moles per unit volume of a species. Its unit quantity is
concentration.

Mole fraction of speciesn
(in the
Species... category) is the number of moles of a species in one mole of the mixture.

Mole fraction of HCN, Mole fraction of NH3, Mole fraction of NO, Mole fraction of N2O
(in the
NOx... category) are the number of moles of HCN, NH
, NO, and N
O in one mole of the mixture. The
Mole fraction of HCN and the
Mole fraction of NH3 will appear only if you are modeling fuel NOx. See
this section in the separate
Theory Guide for details.

Mole fraction of soot
(in the
Soot... category) is the number of moles of soot in one mole of the mixture.

Molecular Prandtl Number
(in the
Properties... category) is the ratio
.

Molecular Viscosity
(in the
Properties... category) is the laminar viscosity of the fluid. Viscosity,
, is defined by the ratio of shear stress to the rate of shear. Its unit quantity is
viscosity. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list. For granular phases, this is equivalent to the solids shear viscosity
in
this equation in the separate
Theory Guide.

Momentum Thickness Re (
)
(in the
Turbulence... category) is based on the momentum thickness of the boundary layer. The SST transition model is considering a non local empirical correlation for the value of
in the freestream, based on turbulence intensity, pressure gradient, etc... and a transport equation to allow the freestream value to diffuse into the boundary layer.

NH3 Density, NO Density, N2O Density
(in the
NOx... category) are the mass per unit volume of NH
, NO and N
O. The unit quantity for each is
density. The
NH3 Density will appear only if you are modeling fuel NOx. See
this section in the separate
Theory Guide for details.

NOx...
contains quantities related to the NOx model. See Section
21.1 for details about this model.

Partition Boundary Cell Distance
(in the
Mesh... category) is the smallest number of cells which must be traversed to reach the nearest partition (interface) boundary.

Partition Neighbors
(in the
Cell Info... category) is the number of adjacent partitions (i.e., those that share at least one partition boundary face (interface)). It gives a measure of the number of messages that will have to be generated for parallel processing.

Pdf...
contains quantities related to the nonpremixed combustion model, which is described in Chapter
16.

PDF Table Adiabatic Enthalpy
is the adiabatic enthalpy corresponding to the cell value of mixture fraction. For single mixture fraction cases it is given by the following equation:

(31.423) 
and for cases involving a secondary stream it is given by the following equation:

(31.424) 
where 





= 
mixture fraction 


= 
secondary mixture fraction 


= 
total enthalpy of the fuel stream 


= 
total enthalpy of the secondary stream 


= 
total enthalpy of the oxidizer stream 
For adiabatic cases the
PDF Table Adiabatic Enthalpy is equal to the value of Enthalpy. The unit of measurement is specificenergy.

PDF Table Heat Loss/Gain
is given by the following equation:

(31.425) 
if the cell enthalpy is less than the adiabatic enthalpy, and by the following equation:

(31.426) 
if the cell enthalpy is higher than adiabatic
where 





= 
total enthalpy 


= 
the PDF Table Adiabatic Enthalpy 


= 
the minimum Enthalpy defined in the PDF table 


= 
the maximum Enthalpy defined in the PDF table 
The
PDF Table Heat Loss/Gain is dimensionless and ranges in value from 1, when
is equal to
, to +1, when
is equal to
. If H is equal to the adiabatic enthalpy it will be 0.

Phases...
contains quantities for reporting the volume fraction of each phase. See Chapter
24 for details.

Pitchwise Coordinate
(in the
Mesh... category) is the normalized (dimensionless) coordinate in the circumferential (pitchwise) direction. Its value varies from
to
.

Preconditioning Reference Velocity
(in the
Velocity... category) is the reference velocity used in the coupled solver's preconditioning
algorithm. See
this section in the separate
Theory Guide for details.

Premixed Combustion...
contains quantities related to the premixed combustion model, which is described in Chapter
17.

Pressure...
includes quantities related to a normal force per unit area (the impact of the gas molecules on the surfaces of a control volume).

Pressure Coefficient
(in the
Pressure... category) is a dimensionless parameter defined by the equation

(31.427) 
where
is the static pressure,
is the reference pressure, and
is the reference dynamic pressure defined by
. The reference pressure, density, and velocity are defined in the
Reference Values task page.

Product Formation Rate
(in the
Premixed Combustion... category) is the source term in the progress variable transport equation (
in
this equation in the separate
Theory Guide). Its unit quantity is
timeinverse.

Production of k
(in the
Turbulence... category) is the rate of production of turbulence kinetic energy (times density). Its unit quantity is
turbkineticenergyproduction. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Progress Variable
(in the
Premixed Combustion... category) is a normalized mass fraction of the combustion products (
) or unburnt mixture products (
), as defined by
this equation in the separate
Theory Guide.

Properties...
includes material property quantities for fluids and solids.

Rate of NO
(in the
NOx... category) is the overall rate of formation of NO due to all active NO formation pathways (e.g., thermal, prompt, etc.).

Rate of Nuclei
(in the
Soot... category) is the overall rate of formation of nuclei.

Rate of N2OPath NO
(in the
NOx... category) is the rate of formation of NO due to the N2O pathway only (only available when N2O pathway is active).

Rate of Prompt NO
(in the
NOx... category) is the rate of formation of NO due to the prompt pathway only (only available when prompt pathway is active).

Rate of Reburn NO
(in the
NOx... category) is the rate of formation of NO due to the reburn pathway only (only available when reburn pathway is active).

Rate of SNCR NO
(in the
NOx... category) is the rate of formation of NO due to the SNCR pathway only (only available when SNCR pathway is active).

Rate of Soot
(in the
Soot... category) is the overall rate of formation of soot mass.

Rate of Thermal NO
(in the
NOx... category) is the rate of formation of NO due to the thermal pathway only (only available when thermal pathway is active).

Rate of Fuel NO
(in the
NOx... category) is the rate of formation of NO due to the fuel pathway only (only available when fuel pathway is active).

Rate of USER NO
(in the
NOx... category) is the rate of formation of NO due to user defined rates only (only available when UDF rates are added).

Radial Coordinate
(in the
Mesh... category) is the length of the radius vector in the polar coordinate system. The radius vector is defined by a line segment between the node and the axis of rotation. You can define the rotational axis in the
Fluid dialog box. (See also Section
31.2.) The unit quantity for
Radial Coordinate is
length.

Radial Pull Velocity
(in the
Solidification/Melting... category) is the radialdirection component of the pull velocity for the solid material in a continuous casting process. Its unit quantity is
velocity.

Radial Velocity
(in the
Velocity... category) is the component of velocity in the radial direction. (See Section
31.2 for details.) The unit quantity for
Radial Velocity is
velocity. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

RadialWall Shear Stress
(in the
Wall Fluxes... category) is the radial component of the force acting tangential to the surface due to friction. Its unit quantity is
pressure.

Radiation...
includes quantities related to radiation heat transfer. See Section
13.3 for details about the radiation models available in
ANSYS FLUENT.

Radiation Heat Flux
(in the
Wall Fluxes... category) is the rate of radiation heat transfer through the control surface. It is calculated by the solver according to the specified radiation model. Heat flux out of the domain is negative, and heat flux into the domain is positive. The unit quantity for
Radiation Heat Flux is
heatflux.

Radiation Temperature
(in the
Radiation... category) is the quantity
, defined by

(31.428) 
where
is the
Incident Radiation. The unit quantity for
Radiation Temperature is
temperature.

Rate of Reactionn
(in the
Reactions... category) is the effective rate of progress of
th reaction. For the finiterate model, the value is the same as the
Kinetic Rate of Reactionn. For the eddydissipation model, the value is equivalent to the
Turbulent Rate of Reactionn. For the finiterate/eddydissipation model, it is the lesser of the two.
For particle reactions it is the global rate of the particle reaction n expressed in kmol/s/m3. This is computed as
where
is the rate of particle species depletion (or generation) given by
this equation in the separate
Theory Guide ,
is the particle species molecular weight, and
is the cell volume.

Reactions...
includes quantities related to finiterate reactions. See Chapter
15 for information about modeling finiterate reactions.

Reduced Temperature
(in the
Properties... category) is the ratio
of the fluid temperature
divided by the critical temperature
. The reduced temperature
is available only with the AngierRedlichKwong real gas model.

Reduced Pressure
(in the
Properties... category) is the ratio
of the fluid pressure
divided by the critical pressure
. The reduced pressure
is available only with the AngierRedlichKwong real gas model.

Reflected Radiation Flux (Bandn)
(in the
Wall Fluxes... category) is the amount of radiative heat flux reflected by a semitransparent wall for a particular band of radiation. Its unit quantity is
heatflux.

Reflected Visible Solar Flux, Reflected IR Solar Flux
(in the
Wall Fluxes... category) is the amount of solar heat flux reflected by a semitransparent wall for a visible or infrared (IR) radiation.

Refractive Index
(in the
Radiation... category) is a nondimensional parameter defined as the ratio of the speed of light in a vacuum to that in a material. See
this section in the separate
Theory Guide for details.

Relative Axial Velocity
(in the
Velocity... category) is the axialdirection component of the velocity relative to the reference frame motion. See Section
31.2 for details. The unit quantity for
Relative Axial Velocity is
velocity.

Relative Humidity
(in the
Species... category) is the ratio of the partial pressure of the water vapor actually present in an airwater mixture to the saturation pressure of water vapor at the mixture temperature.
ANSYS FLUENT computes the saturation pressure,
, from the following equation [
65]:

(31.429) 
where 

= 
22.089 MPa 


= 
647.286 K 


= 



= 



= 



= 



= 



= 



= 



= 



= 
0.01 


= 
338.15 K 

Relative Length Scale (DES)
(in the
Turbulence... category) is defined by

(31.430) 
where
is an RANSbased length scale, and
is an LESbased length scale. All of the cells inside the domain in which
belong to the LES region, and all of the cells inside the domain in which
belong to the RANS region. If the
Delayed DES option is enabled (default option), the relative length scale is defined by:

(31.431) 
where F is based on the delaying function considered by the DES model (
for the DESSA model and the DESRKE model and
for the DESSST model). It is equal to zero inside the boundary layer and equal to one outside.

Relative Mach Number
(in the
Velocity... category) is the nondimensional ratio of the relative velocity and speed of sound.

Relative Radial Velocity
(in the
Velocity... category) is the radialdirection component of the velocity relative to the reference frame motion. (See Section
31.2 for details.) The unit quantity for
Relative Radial Velocity is
velocity.

Relative Swirl Velocity
(in the
Velocity... category) is the tangentialdirection component of the velocity relative to the reference frame motion, in an axisymmetric swirling flow. (See Section
31.2 for details.) The unit quantity for
Relative Swirl Velocity is
velocity.

Relative Tangential Velocity
(in the
Velocity... category) is the tangentialdirection component of the velocity relative to the reference frame motion. (See Section
31.2 for details.) The unit quantity for
Relative Tangential Velocity is
velocity.

Relative Total Pressure
(in the
Pressure... category) is the stagnation pressure computed using relative velocities instead of absolute velocities; i.e., for incompressible flows the dynamic pressure would be computed using the relative velocities. (See Section
31.2 for more information about relative velocities.) The unit quantity for
Relative Total Pressure is
pressure.

Relative Total Temperature
(in the
Temperature... category) is the stagnation temperature computed using relative velocities instead of absolute velocities. (See Section
31.2 for more information about relative velocities.) The unit quantity for
Relative Total Temperature is
temperature.

Relative Velocity Angle
(in the
Velocity... category) is similar to the
Velocity Angle except that it uses the relative tangential velocity, and is defined as

(31.432) 
Its unit quantity is
angle.

Relative Velocity Magnitude
(in the
Velocity... category) is the magnitude of the relative velocity vector instead of the absolute velocity vector. The relative velocity (
) is the difference between the absolute velocity (
) and the mesh velocity. For simple rotation, the relative velocity is defined as

(31.433) 
where
is the angular velocity of a rotating reference frame about the origin and
is the position vector. (See also Section
31.2.) The unit quantity for
Relative Velocity Magnitude is
velocity.

Relative X Velocity, Relative Y Velocity, Relative Z Velocity
(in the
Velocity... category) are the
,
, and
direction components of the velocity relative to the reference frame motion. (See Section
31.2 for details.) The unit quantity for these variables is
velocity.

Residuals...
contains different quantities for the pressurebased and densitybased solvers:
In the densitybased solvers, this category includes the corrections to the primitive variables pressure, velocity, temperature, and species, as well as the time rate of change of the corrections to these primitive variables for the current iteration (i.e., residuals). Corrections are the changes in the variables between the current and previous iterations and residuals are computed by dividing a cell's correction by its physical time step. The total residual for each variable is the summation of the Euler, viscous, and dissipation contributions. The dissipation components are the vector components of the fluxlike, facebased dissipation operator.
In the pressurebased solver, only the
Mass Imbalance in each cell is reported (unless you have requested others, as described in Section
26.13.1). At convergence, this quantity should be small compared to the average mass flow rate.

RMS quantityn
(in the
Unsteady Statistics... category) is the root mean squared value of a solution variable (e.g.,
Static Pressure). See Section
26.12.4 for details.

Rothalpy
(in the
Temperature... category) is defined as

(31.434) 
where
is the enthalpy,
is the relative velocity magnitude, and
is the magnitude of the rotational velocity
.

Scalarn
(in the
User Defined Scalars... category) is the value of the
th scalar quantity you have defined as a userdefined scalar. See the separate UDF manual for more information about userdefined scalars.

Scalar Dissipation
(in the
Pdf... category) is one of two parameters that describes the species mass fraction and temperature for a laminar flamelet in mixture fraction spaces. It is defined as

(31.435) 
where
is the mixture fraction and
is a representative diffusion coefficient (see
this section in the separate
Theory Guide for details). Its unit quantity is
timeinverse.

Scattering Coefficient
(in the
Radiation... category) is the property of a medium that describes the amount of scattering of thermal radiation per unit path length for propagation in the medium. It can be interpreted as the inverse of the mean free path that a photon will travel before undergoing scattering (if the scattering coefficient does not vary along the path). The unit quantity for
Scattering Coefficient is
lengthinverse.

Secondary Mean Mixture Fraction
(in the
Pdf... category) is the mean ratio of the secondary stream mass fraction to the sum of the fuel, secondary stream, and oxidant mass fractions. It is the secondarystream conserved scalar that is calculated by the nonpremixed combustion model. See
this section in the separate
Theory Guide.

Secondary Mixture Fraction Variance
(in the
Pdf... category) is the variance of the secondary stream mixture fraction that is solved for in the nonpremixed combustion model. See
this section in the separate
Theory Guide.

Sensible Enthalpy
(in the
Temperature... category) is available when any of the species models are active and displays only the thermal (sensible) enthalpy.

Skin Friction Coefficient
(in the
Wall Fluxes... category) is a nondimensional parameter defined as the ratio of the wall shear stress and the reference dynamic pressure

(31.436) 
where
is the wall shear stress, and
and
are the reference density and velocity defined in the
Reference Values task page. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Solar Heat Flux
(in the
Wall Fluxes... category) is the rate of solar heat transfer through the control surface. Heat flux out of the domain is negative and heat flux into the domain is positive.

Solidification/Melting...
contains quantities related to solidification and melting.

Soot...
contains quantities related to the
Soot model, which is described in Section
21.3.

Soot Density
(in the
Soot... category) is the mass per unit volume of soot. The unit quantity is
density. See
this section in the separate
Theory Guide for details.

Sound Speed
(in the
Properties... category) is the acoustic speed. It is computed from
. Its unit quantity is
velocity.


Note that for the real gas models the sound speed is computed accordingly by the appropriate equation of state formulation.


Spanwise Coordinate
(in the
Mesh... category) is the normalized (dimensionless) coordinate in the spanwise direction, from hub to casing. Its value varies from
to
.

speciesn Source Term
(in the
Species... category) is the source term in each of the species transport equations due to reactions. The unit quantity is always kg/m
s.

Species...
includes quantities related to species transport and reactions.

Specific Dissipation Rate (Omega)
(in the
Turbulence... category) is the rate of dissipation of turbulence kinetic energy in unit volume and time. Its unit quantity is
timeinverse.

Specific Heat (Cp)
(in the
Properties... category) is the thermodynamic property of specific heat at constant pressure. It is defined as the rate of change of enthalpy with temperature while pressure is held constant. Its unit quantity is
specificheat.

Specific Heat Ratio (gamma)
(in the
Properties... category) is the ratio of specific heat at constant pressure to the specific heat at constant volume.

Spinodal Temperature
(in the
Properties... category) is the temperature at which the derivative of pressure with respect to volume becomes positive. The
spinodal temperature defines the point beyond which the equation of state is no longer valid for the gas phase. If the temperature of your case approaches the
spinodal temperature in some regions, this indicates that the flow conditions in these regions may fall inside the saturation dome. The
spinodal temperature is available only with the AngierRedlichKwong real gas model.

Stored Cell Partition
(in the
Cell Info... category) is an integer identifier designating the partition to which a particular cell belongs. In problems in which the mesh is divided into multiple partitions to be solved on multiple processors using the parallel version of
ANSYS FLUENT, the partition ID can be used to determine the extent of the various groups of cells. The active cell partition is used for the current calculation, while the stored cell partition (the last partition performed) is used when you save a case file. See Section
32.5.4 for more information.

Static Pressure
(in the
Pressure... category) is the static pressure of the fluid. It is a gauge pressure expressed relative to the prescribed operating pressure. The absolute pressure is the sum of the
Static Pressure and the operating pressure. Its unit quantity is
pressure.

Static Temperature
(in the
Temperature... and
Premixed Combustion... categories) is the temperature that is measured moving with the fluid. Its unit quantity is
temperature.
Note that
Static Temperature will appear in the
Premixed Combustion... category only for adiabatic premixed combustion calculations. See Section
17.5.

Strain Rate
(in the
Derivatives... category) relates shear stress to the viscosity. Also called the shear rate (
in Equation
8.417), the strain rate is related to the second invariant of the rateofdeformation tensor
. Its unit quantity is
timeinverse. In 3D Cartesian coordinates, the strain rate,
, is defined as
For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Stream Function
(in the
Velocity... category) is formulated as a relation between the streamlines and the statement of conservation of mass. A streamline is a line that is tangent to the velocity vector of the flowing fluid. For a 2D planar flow, the stream function,
, is defined such that

(31.438) 
where
is constant along a streamline and the difference between constant values of stream function defining two streamlines is the mass rate of flow between the streamlines.
The accuracy of the stream function calculation is determined by the text command
/display/set/nstreamfunc.

Stretch Factor
(in the
Premixed Combustion... category) is a nondimensional parameter that is defined as the probability of unquenched flamelets (
in
this equation in the separate
Theory Guide).

Subgrid Filter Length
(in the
Turbulence... category) is a mixing length for subgrid scales of the LES turbulence model (defined as
in
this equation in the separate
Theory Guide).

Subgrid Kinetic Energy
(in the
Turbulence... category) is the turbulence kinetic energy per unit mass of the unresolved eddies,
, calculated using the LES turbulence model. It is defined as

(31.439) 
Its unit quantity is
turbulentkineticenergy.

Subgrid Turbulent Viscosity
(in the
Turbulence... category) is the turbulent (dynamic) viscosity of the fluid calculated using the LES turbulence model. It expresses the proportionality between the anisotropic part of the subgridscale stress tensor and the rateofstrain tensor. (See
this equation in the separate
Theory Guide.) Its unit quantity is
viscosity.

Subgrid Turbulent Viscosity Ratio
(in the
Turbulence... category) is the ratio of the subgrid turbulent viscosity of the fluid to the laminar viscosity, calculated using the LES turbulence model.

Surface Acoustic Power
(in the
Acoustics... category) is the
Acoustic Power per unit area generated by boundary layer turbulence (see
this equation in the separate
Theory Guide). It is available only when the
Broadband Noise Sources acoustics model is being used. Its unit quantity is
power per
area.

Surface Acoustic Power Level (dB)
(in the
Acoustics... category) is the
Acoustic Power per unit area generated by boundary layer turbulence, and represented in dB (see
this equation in the separate
Theory Guide). It is available only when the
Broadband Noise Sources acoustics model is being used.

Surface Cluster ID
(in the
Radiation... category) is used to view the distribution of surface clusters in the domain. Each cluster has a unique integer number (ID) associated with it.

Surface Coverage of speciesn
(in the
Species... category) is the amount of a surface species that is deposited on the substrate at a specific point in time.

Surface Deposition Rate of speciesn
(in the
Species... category) is the amount of a surface species that is deposited on the substrate. Its unit quantity is
massflux.

Surface dpdt RMS
(in the
Acoustics... category) is the RMS value of the timederivative of static pressure (
). It is available when the
FfowcsWilliams & Hawkings acoustics model is being used.

Surface Heat Transfer Coef.
(in the
Wall Fluxes... category), as defined in
ANSYS FLUENT, is given by the equation

(31.440) 
where
is the combined convective and radiative heat flux,
is the wall temperature, and
is the reference temperature defined in the
Reference Values task page. Please note that
is a constant value that should be representative of the problem. Its unit quantity is the
heattransfer
coefficient.

Surface Incident Radiation
(in the
Wall Fluxes... category) is the net incoming radiation heat flux on a surface. Its unit quantity is
heatflux.

Surface Nusselt Number
(in the
Wall Fluxes... category) is a local nondimensional coefficient of heat transfer defined by the equation

(31.441) 
where
is the heat transfer coefficient,
is the reference length defined in the
Reference Values task page, and
is the molecular thermal conductivity.

Surface Stanton Number
(in the
Wall Fluxes... category) is a nondimensional coefficient of heat transfer defined by the equation

(31.442) 
where
is the heat transfer coefficient,
and
are reference values of density and velocity defined in the
Reference Values task page, and
is the specific heat at constant pressure.

Swirl Pull Velocity
(in the
Solidification/Melting... category) is the tangentialdirection component of the pull velocity for the solid material in a continuous casting process. Its unit quantity is
velocity.

Swirl Velocity
(in the
Velocity... category) is the tangentialdirection component of the velocity in an axisymmetric swirling flow. See Section
31.2 for details. The unit quantity for
Swirl Velocity is
velocity. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

SwirlWall Shear Stress
(in the
Wall Fluxes... category) is the swirl component of the force acting tangential to the surface due to friction. Its unit quantity is
pressure.

Tangential Velocity
(in the
Velocity... category) is the velocity component in the tangential direction. (See Section
31.2 for details.) The unit quantity for
Tangential Velocity is
velocity.

Temperature...
indicates the quantities associated with the thermodynamic temperature of a material.

Thermal Conductivity
(in the
Properties... category) is a parameter (
) that defines the conduction rate through a material via Fourier's law (
). A large thermal conductivity is associated with a good heat conductor and a small thermal conductivity with a poor heat conductor (good insulator). Its unit quantity is
thermalconductivity.

Thermal Diff Coef of speciesn
(in the
Species... category) is the thermal diffusion coefficient for the
th species (
in Equations
8.91,
8.93, and
8.97). Its unit quantity is
viscosity.

Time Step
(in the
Residuals... category) is the local time step of the cell,
, at the current iteration level. Its unit quantity is
time.

Time Step Scale
(in the
Species... category) is the factor by which the time step is reduced for the stiff chemistry solver (available in the densitybased solver only). The time step is scaled down based on an eigenvalue and positivity analysis.

Total Energy
(in the
Temperature... category) is the total energy per unit mass. Its unit quantity is
specificenergy. For all species models, plots of
Total Energy include the sensible, chemical and kinetic energies. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Total Enthalpy
(in the
Temperature... category) is defined as
where
is the
Enthalpy, as defined in
this equation in the separate
Theory Guide , and
is the velocity magnitude. Its unit quantity is
specificenergy. For all species models, plots of
Total Enthalpy consist of the sensible, chemical and kinetic energies. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Total Enthalpy Deviation
(in the
Temperature... category) is the difference between
Total Enthalpy and the reference enthalpy,
, where
is the reference enthalpy defined in the
Reference Values task page. However, for nonpremixed and partially premixed models,
Total Enthalpy Deviation is the difference between
Total Enthalpy and total adiabatic enthalpy (total enthalpy where no heat loss or gain occurs). The unit quantity for
Total Enthalpy Deviation is
specificenergy. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Total Pressure
(in the
Pressure... category) is the pressure at the thermodynamic state that would exist if the fluid were brought to zero velocity and zero potential. For compressible flows, the total pressure is computed using isentropic relationships. For constant
, this reduces to:

(31.443) 
where
is the static pressure,
is the ratio of specific heats, and M is the Mach number. For incompressible flows (constant density fluid), we use Bernoulli's equation,
, where
is the local dynamic pressure. Its unit quantity is
pressure.


Note that in the postprocessing, the total pressure is presented as gauge pressure, for compressible and incompressible flows. If the total absolute pressure is needed, then add the value of the reference pressure to the total gauge pressure.


Total Surface Heat Flux
(in the
Wall Fluxes... category) is the rate of total heat transfer through the control surface. It is calculated by the solver according to the boundary conditions being applied at that surface. By definition, heat flux out of the domain is negative, and heat flux into the domain is positive. The unit quantity for
Total Surface Heat Flux is
heatflux.

Total Temperature
(in the
Temperature... category) is the temperature at the thermodynamic state that would exist if the fluid were brought to zero velocity. For compressible flows, the total temperature is computed from the total enthalpy using the current
method (specified in the
Create/Edit Materials dialog box). For incompressible flows, the total temperature is equal to the static temperature. The unit quantity for
Total Temperature is
temperature.

Transmitted Radiation Flux (Bandn)
(in the
Wall Fluxes... category) is the amount of radiative heat flux transmitted by a semitransparent wall for a particular band of radiation. Its unit quantity is
heatflux.

Transmitted Visible Solar Flux, Transmitted IR Solar Flux
(in the
Wall Fluxes... category) is the amount of solar heat flux transmitted by a semitransparent wall for a visible or infrared radiation.

Turbulence...
includes quantities related to turbulence. See Chapter
12 for information about the turbulence models available in
ANSYS FLUENT.

Turbulence Intensity
(in the
Turbulence... category) is the ratio of the magnitude of the RMS turbulent fluctuations to the reference velocity:

(31.444) 
where
is the turbulence kinetic energy and
is the reference velocity specified in the
Reference Values task page. The reference value specified should be the mean velocity magnitude for the flow. Note that turbulence intensity can be defined in different ways, so you may want to use a custom field function for its definition. See Section
31.5 for more information.

Turbulent Dissipation Rate (Epsilon)
(in the
Turbulence... category) is the turbulent dissipation rate. Its unit quantity is
turbulentenergydissrate. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Turbulent Flame Speed
(in the
Premixed Combustion... category) is the turbulent flame speed computed by
ANSYS FLUENT using
this equation in the separate
Theory Guide. Its unit quantity is
velocity.

Turbulent Kinetic Energy (k)
(in the
Turbulence... category) is the turbulence kinetic energy per unit mass defined as

(31.445) 
Its unit quantity is
turbulentkineticenergy. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Turbulent Rate of Reactionn
(in the
Reactions... category) is the rate of progress of the
th reaction computed by
this equation or
this equation (in the separate
Theory Guide). For the "eddydissipation'' model, the value is the same as the
Rate of Reactionn. For the "finiterate'' model, the value is zero.

Turbulent Reynolds Number (Re_y)
(in the
Turbulence... category) is a nondimensional quantity defined as

(31.446) 
where
is turbulence kinetic energy,
is the distance to the nearest wall, and
is the laminar viscosity.

Turbulent Viscosity
(in the
Turbulence... category) is the turbulent viscosity of the fluid computed using the turbulence model. Its unit quantity is
viscosity. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Turbulent Viscosity Ratio
(in the
Turbulence... category) is the ratio of turbulent viscosity to the laminar viscosity.

udmn
(in the
User Defined Memory... category) is the value of the quantity in the
th userdefined memory location.

Unburnt Fuel Mass Fraction
(in the
Premixed Combustion... category) is the mass fraction of unburnt fuel. This function is available only for nonadiabatic models.

Unsteady Statistics...
includes mean and root mean square (RMS) values of solution variables derived from transient flow calculations.

User Defined Memory...
includes quantities that have been allocated to a userdefined memory location. See the separate UDF Manual for details about userdefined memory.

UserDefined Scalars...
includes quantities related to userdefined scalars. See the separate UDF Manual for information about using userdefined scalars.

UU Reynolds Stress
(in the
Turbulence... category) is the
stress.

UV Reynolds Stress
(in the
Turbulence... category) is the
stress.

UW Reynolds Stress
(in the
Turbulence... category) is the
stress.

Variance of Species
(in the
NOx... category) is the variance of the mass fraction of a selected species in the flow field. It is calculated from
this equation in the separate
Theory Guide.

Variance of Species 1, Variance of Species 2
(in the
NOx... category) are the variances of the mass fractions of the selected species in the flow field. They are each calculated from
this equation in the separate
Theory Guide.

Variance of Temperature
(in the
NOx... category) is the variance of the normalized temperature in the flow field. It is calculated from
this equation in the separate
Theory Guide.

Velocity...
includes the quantities associated with the rate of change in position with time. The instantaneous velocity of a particle is defined as the first derivative of the position vector with respect to time,
, termed the velocity vector,
.

Velocity Angle
(in the
Velocity... category) is defined as follows:
For a 2D model,

(31.447) 
For a 2D or axisymmetric model,

(31.448) 
For a 3D model,

(31.449) 
Its unit quantity is
angle.

Velocity Magnitude
(in the
Velocity... category) is the speed of the fluid. Its unit quantity is
velocity. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Volume fraction
(in the
Phases... category) is the volume fraction of the selected phase in the
Phase dropdown list.

Vorticity Magnitude
(in the
Velocity... category) is the magnitude of the vorticity vector. Vorticity
is a measure of the rotation of a fluid element as it moves in the flow field, and is defined as the curl of the velocity vector:

(31.450) 

VV Reynolds Stress
(in the
Turbulence... category) is the
stress.

VW Reynolds Stress
(in the
Turbulence... category) is the
stress.

Wall Fluxes...
includes quantities related to forces and heat transfer at wall surfaces.

Wall Func. Heat Tran. Coef.
is defined by the equation

(31.451) 
where
is the specific heat,
is the turbulence kinetic energy at point
, and
is the dimensionless lawofthewall temperature defined in
this equation in the separate
Theory Guide.


Note that
ANSYS FLUENT reports wall functions heat transfer coefficient (Equation
31.451) as zero for adiabatic walls.


Wall Shear Stress
(in the
Wall Fluxes... category) is the force acting tangential to the surface due to friction. Its unit quantity is
pressure. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Wall Temperature (Inner Surface)
(in the
Temperature... category) is the temperature on the inner surface of a wall (corresponding to the side of the wall surface away from the adjacent fluid or solid cell zone). Note that wall thermal boundary conditions are applied on this surface. See also Figure
7.3.20. The unit quantity for
Wall Temperature (Inner Surface) is
temperature.

Wall Temperature (Outer Surface)
(in the
Temperature... category) is the temperature on the outer surface of a wall (corresponding to the side of the wall surface toward the adjacent fluid or solid cell zone). Note that wall thermal boundary conditions are applied on the
Inner Surface. See also Figure
7.3.20. The unit quantity for
Wall Temperature (Outer Surface) is
temperature.

Wall Yplus
(in the
Turbulence... category) is a nondimensional parameter defined by the equation

(31.452) 
where
is the friction velocity,
is the distance from point
to the wall,
is the fluid density, and
is the fluid viscosity at point
. See
this section in the separate
Theory Guide for details. For multiphase models, this value corresponds to the selected phase in the
Phase dropdown list.

Wall Ystar
(in the
Turbulence... category) is a nondimensional parameter defined by the equation

(31.453) 
where
is the turbulence kinetic energy at point
,
is the distance from point
to the wall,
is the fluid density, and
is the fluid viscosity at point
. See
this section in the separate
Theory Guide for details.

WW Reynolds Stress
(in the
Turbulence... category) is the
stress.

XCoordinate, YCoordinate, ZCoordinate
(in the
Mesh... category) are the Cartesian coordinates in the
axis,
axis, and
axis directions respectively. The unit quantity for these variables is
length.

X Face Area, Y Face Area, Z Face Area
(in the
Mesh... category) are the components of the face area vector for noninternal faces (i.e., faces that only have
c0 and no
c1). The values are stored on the face itself and used when required. These variables are intended only for zone surfaces and not for other surfaces created for postprocessing.

X Pull Velocity, Y Pull Velocity, Z Pull Velocity
(in the
Solidification/Melting... category) are the
,
, and
components of the pull velocity for the solid material in a continuous casting process. The unit quantity for each is
velocity.

X Velocity, Y Velocity, Z Velocity
(in the
Velocity... category) are the components of the velocity vector in the
axis,
axis, and
axis directions, respectively. The unit quantity for these variables is
velocity. For multiphase models, these values correspond to the selected phase in the
Phase dropdown list.

XVorticity, YVorticity, ZVorticity
(in the
Velocity... category) are the
,
, and
components of the vorticity vector.

XWall Shear Stress, YWall Shear Stress, ZWall Shear Stress
(in the
Wall Fluxes... category) are the
,
, and
components of the force acting tangential to the surface due to friction. The unit quantity for these variables is
pressure. For multiphase models, these values correspond to the selected phase in the
Phase dropdown list.