The
Species Model dialog box allows you to set parameters related to the calculation of species transport and combustion. See Sections
15.1.2,
15.2.2,
15.3.1,
17.2,
18.2, and
19.2 for details about the items below.
Controls
Model
indicates which model, if any, is used to calculate species transport/combustion.
Off
disables species calculations.
Species Transport
enables the calculation of multi-species transport (either non-reacting or reacting, depending on the selection for
Reactions). See Chapter
15 for details.
Non-Premixed Combustion
enables the calculation of turbulent reacting flow using the non-premixed combustion model. See Chapter
16 for details. This option is available only for turbulent flows using the pressure-based solver.
Premixed Combustion
enables the premixed turbulent combustion model. See Chapter
17 for details. This option is available only for turbulent flows using the pressure-based solver.
Partially Premixed Combustion
enables the partially premixed turbulent combustion model. See Chapter
18 for details. This option is available only for turbulent flows using the pressure-based solver.
Composition PDF Transport
enables the composition PDF transport model. See Chapter
19 for details. This option is available only for turbulent flows using the pressure-based solver.
Reactions
contains options related to the modeling of reacting flow. (This section of the dialog box appears only when
Species Transport or
Composition PDF Transport is the specified
Model.)
Volumetric
enables the calculation of reacting flow using the finite-rate formulation. See Section
15.1 for details.
Wall Surface
enables the calculation of wall surface reactions. See Section
15.2 for details. This item will appear only if
Volumetric is enabled.
Particle Surface
enables the calculation of particle surface reactions. See Section
15.3 for details. This item will appear only if
Volumetric is enabled.
Integration Parameters...
is a command button that opens the
Integration Parameters dialog box. This button appears for the species transport model, when
Volumetric is enabled under
Reactions and
Stiff Chemistry Solver is enabled under
Options or when
Eddy-Dissipation Concept is enabled under
Turbulence-Chemistry Interaction.
Wall Surface Reaction Options
contains additional options for wall surface reactions. This portion of the dialog box appears only if
Wall Surface is enabled under
Reactions.
Heat of Surface Reactions
(if enabled) includes the heat release due to surface reactions in the energy equation. You must remember to set appropriate formation enthalpies (standard state enthalpies) if you enable this option.
Mass Deposition Source
(if enabled) includes the effect of surface mass transfer in the continuity equation.
Aggressiveness Factor
is a numerical factor which controls the robustness and the convergence speed. This value ranges between 0 and 1, where 0 (the default) is the most robust, but results in the slowest convergence.
Options
contains additional options for the
Species Transport model and for the
Composition PDF Transport. (This section will not appear in the dialog box for the other models.)
Inlet Diffusion
includes the diffusion flux of species at inlet.
Diffusion Energy Source
(if enabled) includes the effect of enthalpy transport due to species diffusion in the energy equation.
Full Multicomponent Diffusion
enables the full multicomponent diffusion model. See Section
8.9.2 for details.
Thermal Diffusion
enables the thermal diffusion model. See Section
8.9.3 for details.
Stiff Chemistry Solver
enables the calculations for modeling stiff laminar flames. See Section
15.1.7 for details.
Liquid Micro-Mixing
is used to model liquid reactions. When the
Liquid Micro-Mixing model is invoked,
ANSYS FLUENT uses the
volume-weighted-mixing-law formula to calculate the density.
KINetics From Reaction Design
enables the use of reaction rates-of-production from Reaction Design's KINetics module, coupled to
ANSYS FLUENT's ISAT algorithm.
Include Temperature Fluctuations
enables the calculation of the multi-mode energy equation. This option is available when the composition PDF transport model is selected.
Mixture Properties
contains controls and information about the mixture being modeled. This section of the dialog box will not appear if
Premixed Combustion is the selected under
Model.
Mixture Material
contains a drop-down list of available mixture materials. When you first enable the
Species Transport model, you can choose from all of the mixture materials defined in the database, or you can choose a "template'' and define your own material. (Click
View... to open the
Database Materials dialog box and check the properties of the mixture material selected in the list.) See Section
15.1.2 for details.
When you use the
Non-Premixed Combustion or
Partially Premixed Combustion model, this list will be inactive. The mixture material for a non-premixed or partially premixed combustion calculation will be determined from the content of the PDF file generated in
ANSYS FLUENT using the
PDF Options parameters.
Number of Volumetric Species
displays the number of gas-phase species in the selected
Mixture Material. This is an informational display only; you cannot edit this value.
Number of Solid Species
displays the number of solid species defined in the selected
Mixture Material. This is an informational display only; you cannot edit this value. (This list will appear only for
Species Transport models involving
Wall Surface reactions.)
Number of Site Species
displays the number of site species defined in the selected
Mixture Material. This is an informational display only; you cannot edit this value. (This list will appear only for
Species Transport models involving
Wall Surface reactions.)
Turbulence-Chemistry Interaction
indicates which model is to be used for turbulence-chemistry interaction when the
Species Transport model with
Volumetric reactions is used.
Laminar Finite-Rate
computes only the Arrhenius rate (see
this equation in the separate
Theory Guide) and neglects turbulence-chemistry interaction.
Finite-Rate/Eddy-Dissipation
(for turbulent flows) computes both the Arrhenius rate and the mixing rate and uses the smaller of the two.
Eddy-Dissipation Concept
(for turbulent flows) models turbulence-chemistry interaction with detailed chemical mechanisms (see
this equation and
this equation in the separate
Theory Guide).
Options
contains parameters related to the Laminar Finite-Rate or the Eddy-Dissipation Concept model. This section of the dialog box will appear when
Laminar Finite-Rate or the
Eddy-Dissipation Concept is selected for
Turbulence-Chemistry Interaction.
Flow Iterations Per Chemistry Update
specifies how often
ANSYS FLUENT will update the chemistry during the calculation. Increasing the number can reduce the computational expense of the chemistry calculations.
Aggressiveness Factor
is a numerical factor which controls the robustness and the convergence speed. This value ranges between 0 and 1, where 0 (the default) is the most robust, but results in the slowest convergence.
PDF Options
contains options related for the non-premixed combustion model. (This section will appear only if
Non-Premixed Combustion or
Partially-Premixed Combustion is the selected
Model.)
Inlet Diffusion
includes the diffusion flux of species at inlet.
Compressibility Effects
can be enabled to account for cases where substantial pressure changes occur in time and/or space when modeling a non-adiabatic system. See Section
16.2.2 for details.
Liquid Micro-Mixing
is used to model liquid reactions. When the
Liquid Micro-Mixing model is invoked,
ANSYS FLUENT uses the
volume-weighted-mixing-law formula to calculate the density.
Chemistry
tab contains the parameters to define problems using the chemistry model. See Section
16.2 for details.
State Relation
Equilibrium
enables the equilibrium chemistry model. See Section
16.2 for details.
Steady Flamelet
enables the steady laminar flamelet model. See
this section in the separate
Theory Guide for details.
Unsteady Flamelet
enables the Eulerian unsteady laminar flamelet model.
Diesel Unsteady Flamelet
enables the diesel unsteady laminar flamelet model. See Section
16.3.6 for details.
Energy Treatment
Adiabatic
enables adiabatic modeling options for the problem.
Non-Adiabatic
enables nonadiabatic modeling options for the problem. See
this section in the separate
Theory Guide for details.
Stream Options
contains the parameters for the equilibrium chemistry model or the steady laminar flamelet model.
Secondary Stream
includes the secondary inlet stream in the model.
Empirical Fuel Stream
enables parameters to define fuel stream empirically. This option is available only with the full equilibrium chemistry model.
Empirical Secondary Stream
enables parameters to define secondary stream empirically. This option is available only with the full equilibrium chemistry model.
Model Settings
contains a list of parameter settings.
Operating Pressure
specifies the system operating pressure used to calculate the density using the ideal gas law. See Section
16.2.2 for details.
Fuel Stream Rich Flamability Limit
specifies the rich flammability limit for fuel stream when the equilibrium chemistry option is used. You will not set these if you have used the empirical definition option for fuel composition. See Section
16.2.5 for details.
Secondary Stream Flamability Limit
specifies the rich flammability limit for secondary stream when the equilibrium chemistry option is used. You will not set these if you have used the empirical definition option for fuel composition. See Section
16.2.5 for details.
Empirical Fuel Lower Calorific Value
specifies the lower calorific value of fuel stream.
Empirical Fuel Specific Heat
specifies the specific heat value of fuel stream.
Empirical Fuel Molecular Weight
specifies the molecular weight of the fuel stream.
Empirical Secondary Lower Calorific Value
specifies the lower calorific value of secondary stream.
Empirical Secondary Specific Heat
specifies the specific heat value of secondary stream.
Empirical Secondary Molecular Weight
specifies the molecular weight of the secondary stream.
Options
contains options related to the steady flamelet model.
Create Flamelet
enables the
Import CHEMKIN Mechanism... button that opens the
CHEMKIN Mechanism Import dialog box where you can import the
CHEMKIN mechanism and thermodynamic data, to create a flamelet file. This option is available for the steady flamelet model. See Section
16.3 for details.
Import Flamelet
enables the
Import Flamelet File... button that opens the
Select File dialog box (see Section
2.1.6) where you can select the existing flamelet in
ANSYS FLUENT. You can also set the file type parameters to import the existing flamelet in
ANSYS FLUENT. See Section
16.3 for details. This option is available for the steady flamelet model.
File Type
contains the toggle buttons for two flamelet file types.
Standard
enables the import of an ASCII format standard flamelet file.
Oppdif
enables the import of a binary format OPPDIF flamelet file.
CFX-RIF
enables the import of an ASCII format CFX-RIF flamelet file.
Mixture Fraction Method
contains the three methods of computing the mixture fraction profile along the laminar flamelet.
Drake
calculates the mixture fraction using carbon and hydrogen elements.
Bilger
calculates the mixture fraction using hydrocarbon formula.
Nitrogen
calculates the mixture fraction in terms of nitrogen species.
Oppdif Flamelet Type
gives you have a choice of importing
Single or
Multiple OPPDIF files.
Import Flamelet File for Restart...
opens the
Select File dialog box (see Section
2.1.6) in which you can save the existing flamelet in
ANSYS FLUENT to use when running an existing case.
Thermodynamic Database File Name
specifies a path for the thermodynamic database file to be read.
Boundary
tab contains the list of boundary species and related parameters. This is available only for equilibrium chemistry model. See Section
16.4 for details.
Species
contains the list of the species used in the problem..
Fuel
specifies the fuel species.
Oxid
specifies the oxidizing species.
Second
specifies the secondary species.
Boundary Species
allows to specify the species you want to add or remove from the model. You can type the species chemical formula in the text box below it.
Add
adds the species in the model.
Remove
removes the species from the model.
List Available Species
prints a list of all species in the thermodynamic database file (thermo.db) in the console window.
Temperature
specifies the temperature of different streams that you have defined.
Fuel
is the temperature of the fuel inlet in the model.
Oxid
is the temperature of the oxidizer inlet in the model.
Second
is the temperature of the secondary stream inlet in the model.
Specify Species in
allows to define the unit of species concentration.
Mass Fraction
allows to specify the species in terms of mass fraction.
Mole Fraction
allows to specify the species in terms of mole fraction.
Control
tab contains the parameters for exclusion and inclusion of equilibrium species. This is available only for equilibrium chemistry model. See Section
16.5.1 for details.
Species Excluded from Equilibrium
lists the species excluded from equilibrium calculation.
Species Zeroed in Initial Unsteady Flamelet
lists the slow-forming species that are zeroed in the initial flamelet profile.
Add
allows to add equilibrium species.
Remove
allows to remove equilibrium species.
List Available Species
prints a list of all species in the thermodynamic database file in the console window.
Flamelet Controls
allows you to adjust the controls for the flamelet solution. Note that the
Create Flamelet option in the
Chemistry tab must be selected for the
Steady Flamelet model for these controls to be available.
Initial Fourier Number
sets the first time step for the solution.
Fourier Number Multiplier
increases the time step at subsequent times. Every time step after the first is multiplied by this value.
Relative Error Tolerance and Absolute Error Tolerance
specifies the local error controls during numerical integration.
Flamelet Convergence Tolerance
specifies the maximum absolute change in species fraction or temperature at any discrete mixture-fraction.
Maximum Integration Time
specifies the maximum total elapsed time for flamelet calculation.
ANSYS FLUENT will stop the flamelet calculation after the total elapsed time has exceeded this value.
Flamelet
tab allows you to adjust the controls for the flamelet solution. See Section
16.5.2 for details.
Flamelet Parameters
consist of the controls for the flamelet solution.
Number of Grid Points in Flamelet
specifies the number of mixture fraction grid points distributed between the oxidizer (
) and the fuel (
).
Maximum Number of Flamelets
specifies the maximum number of laminar flamelet profiles to be calculated.
Initial Scalar Dissipation
is the scalar dissipation of the first flamelet in the library.
Scalar Dissipation Step
specifies the interval between scalar dissipation values (in s
) for which multiple flamelets will be calculated.
Unsteady Flamelet Parameters
consist of the controls for the unsteady flamelet solution.
Number of Grid Points in Flamelet
specifies the number of mixture fraction grid points distributed between the oxidizer (
) and the fuel (
).
Mixture Fraction Lower Limit for Initial Probability
is the limit at which the unsteady flamelet model temporally convects and diffuses a marker probability equation through a steady-state
ANSYS FLUENT flow-field.
Maximum Scalar Dissipation
is where flamelets extinguish at large scalar dissipation (mixing) rates.
Courant Number
is the number at which
ANSYS FLUENT automatically selects the time step for the probability equation based on this convective Courant number.
Calculate Flamelets
begins the laminar flamelet calculation.
Display Flamelets...
opens the
Flamelet 3D Surfaces dialog box (see Section
16.6.4) from which you can display 2D plots and 3D surfaces showing the variation of species fraction or temperature with the mean mixture fraction or scalar dissipation.
Initialize Unsteady Flamelet Probability
initializes the unsteady flamelet and its probability marker equation.
Display Unsteady Flamelet...
opens the
Flamelet 2D Curves dialog box from which you can display 2D plots of the different variables.
Table
tab contains parameters to create the look-up table. See Section
16.7 for details of the items listed below.
Table Parameters
consist of the controls for the lookup table.
Number of Mean Mixture Fraction Points
is the number of discrete values of
at which the look-up tables will be computed.
Number of Secondary Mixture Fraction Points
is the number of discrete values of
at which the look-up tables will be computed. This option is available only when a secondary stream has been defined.
Number of Mixture Fraction Variance Points
is the number of discrete values of
at which the look-up tables will be computed. This option is available only when no secondary stream has been defined.
Maximum Number of Species
is the maximum number of species that will be included in the look-up tables.
Number of Mean Enthalpy Points
is the number of discrete values of enthalpy at which the three-dimensional look-up tables will be computed. This input is required only if you are modeling a non-adiabatic system.
Minimum Temperature
is used to determine the lowest temperature for which the look-up tables are generated (see
this figure in the separate
Theory Guide). This option is available only if you are modeling a non-adiabatic system.
Include Equilibrium Flamelet
specifies that an equilibrium flamelet (i.e.,
) will be generated in
ANSYS FLUENT and appended to the flamelet library before the PDF table is calculated. This option is available only when you are generating more than one laminar flamelet.
Calculate PDF Table
generates the look-up table.
Display PDF Table
opens the
PDF Table dialog box where you can display 2D plots and 3D surfaces showing the variation of species mole fraction, density, or temperature with the mean mixture fraction, mixture fraction variance, or enthalpy.
Premixed
tab contains parameters needed to modify the piecewise-linear points. See Section
18.2.2 for the details.
Partially Premixed Mixture Properties
contains the list of properties that you can modify.
Edit... opens the
Quadratic Mixture Fraction dialog box where you can modify the values of the polynomial coefficients.
For each polynomial function of
under
Partially Premixed Mixture Properties you can click
Edit... and specify values for
Coefficient 1,
Coefficient 2,
Coefficient 3, and
Coefficient 4 in the appropriate
Quadratic of Mixture Fraction dialog box.
Premixed Combustion Model Options
contains options for the premixed combustion model. (This section will appear only if
Premixed Combustion is the selected
Model.)
Adiabatic
enables the adiabatic premixed combustion model, which calculates temperature using
this equation in the separate
Theory Guide.
Non-Adiabatic
enables the non-adiabatic premixed combustion model, which calculates temperature using
this equation in the separate
Theory Guide.
Flame Speed Model
contains options for choosing a flame speed model.
Zimont Turbulent Flame Closure
allows you to choose the Zimont turbulent flame closure model.
Extended Coherent Flamelet Model
allows you to choose the Extended Coherent Flamelet model.
Zimont Model Constants
contains model constants for the Zimont premixed combustion model. (This section will appear only if
Premixed Combustion or
Partially Premixed Combustion is the selected
Model and if the
Zimont Turbulent Flame Closure flame speed model is chosen.)
Wall Damping Coefficient
specifies the value of
in
this equation .
Extended Coherent Flamelet Model Constants
contains model constants for the Extended Coherent Flame Model. (This section will appear only if
Premixed Combustion or
Partially Premixed Combustion is the selected
Model and if the
Extended Coherent Flame Model flame speed model is chosen.) See Section
17.4.1 for details.
ITNFS Treatment
contains a drop-down list of the available ITNFS treatments:
constant-delta,
meneveau,
blint,
poinsot, and
constant.
Turbulent Schmidt Number
set the turbulent Schmidt number (Sc
).
Wall Flux Coefficient
set the wall flux coefficient.
PDF Transport Options
contains options for the Composition PDF Transport combustion model. (This section will appear only if
Composition PDF Transport is the selected
Model.)
Lagrangian
solves the composition PDF transport equation by stochastically tracking Lagrangian particles through the domain.
Eulerian
assumes a shape for the PDF, allowing Eulerian transport equations to be derived.
Mixing
tab contains the mixing models.
Mixing Model
contains options to specify the method for modeling molecular diffusion. (This section will appear only if
Composition PDF Transport is the selected
Model.) See
this section in the separate
Theory Guide for details.
Modified Curl
enables the modified curl model for molecular diffusion.
IEM
enables the IEM model for molecular diffusion.
EMST
enables the EMST mixing model for molecular diffusion.
Boundary
tab allows you to define the fuel and oxidizer compositions. This is only available if you select
Eulerian as the
PDF Transport Option.
Species
consists of the fuel species and the oxidizer.
Fuel
is the mole or mass fraction of the fuel stream. The sum of mass or mole fractions of all species in the fuel stream should be 1.
Oxidizer
is the mole or mass fraction of the oxidizer stream. The sum of mass or mole fractions of all species in the fuel oxidizer stream should be 1.
Specify Species in
specifies the species as a
Mass Fraction or
Mole Fraction.
Control
tab contains Lagrangian PDF transport parameters.
PDF Transport Parameters
allows you to set the
Particles Per Cell.
Particles Per Cell
sets the number of PDF particles per cell. Higher values of this parameter will reduce statistical error, but increase computational time.
Local Time Stepping
toggles the calculation of local time steps. If this option is disabled, then you will need to specify the
Time Step directly (see
this equation in the separate
Theory Guide). This option is available for steady-state simulations.
Convection #
specifies the particle convection number (see
in
this equation in the separate
Theory Guide).
Diffusion #
specifies the particle diffusion number (see
in
this equation in the separate
Theory Guide).