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32.3.6 Define/Models/Species/Transport & Reaction...

The Define/Models/Species/Transport & Reaction... menu item opens the Species Model panel.



Species Model Panel


The Species Model panel allows you to set parameters related to the calculation of species transport and combustion. See Sections  14.1.3, 14.2.3, 14.3.2, 16.3, 17.3, and 18.3 for details about the items below.

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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  14 for details.

Non-Premixed Combustion   enables the calculation of turbulent reacting flow using the non-premixed combustion model. See Chapter  15 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  16 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  17 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  18 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 panel 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  14.1 for details.

Wall Surface   enables the calculation of wall surface reactions. See Section  14.2 for details. This item will appear only if Volumetric is enabled.

Particle Surface   enables the calculation of particle surface reactions. See Section  14.3 for details. This item will appear only if Volumetric is enabled.

Integration Parameters...   is a command button that opens the Integration Parameters panel. This button appears for the species transport model, when Volumetric is enabled under Reactions and Stiff Chemistry Solver is enabled under Options or when EDC is enabled under Turbulence-Chemistry Interaction.

Wall Surface Reaction Options   contains additional options for wall surface reactions. This portion of the panel 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.

Options   contains additional options for the Species Transport model and for the Composition PDF Transport. (This section will not appear in the panel 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  14.1.7 for details.

KINetics From Reaction Design   enables use of reaction rates-of-production from Reaction Design's KINetics module, coupled to FLUENT's ISAT algorithm.

Mixture Properties   contains controls and information about the mixture being modeled. This section of the panel 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 Edit... to check the properties of the mixture material selected in the list.) See Section  14.1.3 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 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 Equation  14.1-8) 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   (for turbulent flows) computes only the mixing rate (see Equations  14.1-26 and 14.1-27).

EDC   (for turbulent flows) models turbulence-chemistry interaction with detailed chemical mechanisms (see Equations  14.1-26 and 14.1-27).

Options   contains parameters related to the EDC model. This section of the panel will appear when EDC is selected for Turbulence-Chemistry Interaction.

Flow Iterations Per Chemistry Update   specifies how often FLUENT will update the chemistry during the calculation. Increasing the number can reduce the computational expense of the chemistry calculations.

Volume Fraction Constant   specifies the value of $C_{\xi}$ in Equation  14.1-29.

Time Scale Constant   specifies the value of $C_{\tau}$ in Equation  14.1-30).

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 Section  18.2.3 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.

Mixing Constant   specifies the value of the mixing constant $C_{\phi}$ in Equation  18.2-6 and Equation  18.2-8.

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.

Create Table   enables the parameters to create the PDF table. The panel will expand showing the relevant inputs for the PDF table. See Chapter  15 for the details of these items.

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  15.7.2 for details.

Number of Flow Iterations Per Property Update   specifies how often the density, temperature, and specific heats are updated from the look-up table.

Liquid Micro-Mixing   is used to model liquid reactions. When the Liquid Micro-Mixing model is invoked, FLUENT uses the volume-weighted-mixing-law formula to calculate the density.

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Chemistry   contains the parameters to define problem using the chemistry model. See Section  15.7 for details.

Equilibrium   enables the equilibrium chemistry model. See Section  15.7 for details.

Steady Flamelet   enables the steady laminar flamelet model. See Section  15.3 for details.

Unsteady Flamelet   enables the Eulerian unsteady laminar flamelet model.

Diesel Unsteady Flamelet   enables the diesel unsteady laminar flamelet model. See Section  15.8.6 for details.

Adiabatic   enables adiabatic modeling options for the problem.

Non-Adiabatic   enables nonadiabatic modeling options for the problem. See Section  15.2.3 for details.

Operating Pressure   specifies the system operating pressure used to calculate the density using the ideal gas law. See Section  15.7.2 for details.

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.

Create Flamelet   enables the button to import the CHEMKIN mechanism and thermodynamic data, to create a flamelet file. This option is available for the steady flamelet model.

Import Flamelet   enables the parameters to import the existing flamelet in FLUENT. See Section  15.8 for details. This option is available for the steady flamelet model.

Rich Flammability Limit   contains parameters to define a rich limit on the mixture fraction 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  15.7.5 for details.

Fuel Stream   specifies the rich flammability limit for fuel stream.

Secondary Stream   specifies the rich flammability limit for secondary stream.

Empirical Parameters   allows to define the fuel or secondary stream when the individual species components of the fuel are unknown.
Fuel Lower Calorific Value   specifies the lower calorific value of fuel stream.

Fuel Specific Heat   specifies the specific heat value of fuel stream.

Secondary Lower Calorific Value   specifies the lower calorific value of secondary stream.

Secondary Specific Heat   specifies the specific heat value of secondary stream.

Import CHEMKIN Mechanism...   opens the Chemkin Mechanism Import panel, in which you can read the chemkin mechanism file and thermodynamic database file in FLUENT. See Section  15.8 for details.

Import Flamelet File...   opens the Select File dialog box in which you can select the existing flamelet in FLUENT.

File Type   contains the toggle buttons for two flamelet file types.
Standard   enables the import of standard format of flamelet file.

Oppdif   enables the import of binary format of 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.

Import Flamelet File for Restart...   opens the Select File dialog box in which you can save the existing flamelet in 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  15.9 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.

List Available Species   prints a list of all species in the thermodynamic database file ( thermo.db) in the console window.

Species Units   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.

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.

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.

Control   tab contains the parameters for exclusion and inclusion of equilibrium species. This is available only for equilibrium chemistry model. See Section  15.10.1 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. FLUENTwill 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  15.10.2 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 ( $f=0$) and the fuel ( $f=1$).

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 $^{-1}$) 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 ( $f=0$) and the fuel ( $f=1$).

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 FLUENT flow-field.

Maximum Scalar Dissipation   is where flamelets extinguish at large scalar dissipation (mixing) rates.

Courant Number   is the number at which 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 panel (see Section  15.11.4) 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 panel from which you can display 2D plots of the different variables.

Table tab contains parameters to create the look-up table. See Section  15.12 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 $\overline{f}$ at which the look-up tables will be computed.

Number of Secondary Mixture Fraction Points   is the number of discrete values of $p_{\rm sec}$ 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 $\overline{f^{'2}}$ 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 Figure  15.2.10). This option is available only if you are modeling a non-adiabatic system.

Include Equilibrium Flamelet   specifies that an equilibrium flamelet (i.e., $\chi=0$) will be generated in 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 panel 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 contains parameters needed to modify the piecewise-linear points. See Section  17.3.2 for the details.

Partially Premixed Mixture Properties   contains the list of properties that you can modify. Edit... opens the Quadratic Mixture Fraction panel where you can modify the values of the polynomial coefficients.

For each polynomial function of $\overline{f}$ 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 panel.



Integration Parameters Panel


The Integration Parameters panel allows you to set the parameters for the integration of the chemical source term $S$ in Equation  18.2-10. See Section  18.3.2 for details.

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Integration Method   contains options to choose the method for integration.

ISAT   enables the ISAT option and expands the panel to include inputs for ISAT parameters.

Direct Integration   enables the direct integration method to integrate the chemical source term in the calculation.

ODE Parameters   contains options to specify the error tolerances.
Absolute Error Tolerance   specifies the absolute error tolerance.

Relative Error Tolerance   specifies the relative error tolerance.

Integration parameters   contains inputs required for ISAT integration method.

ISAT Error Tolerance   controls the numerical error in ISAT liner interpolation. Decrease this value to get accurate minor species and pollutant predictions.

Max. Storage   is the maximum RAM used by the ISAT table, and has a default value is 100 MB.

Reference Time Step   specifies the time step size by which the ISAT table is normalized.

Number of Trees   specifies the number of sub-tables within the ISAT table.

Verbosity   specifies the level of detail at which you can monitor the ISAT performance.

Clear ISAT Table   purges the ISAT table.



Chemkin Mechanism Import Panel

The Chemkin Mechanism Import panel allows you to read the chemical kinetic mechanism and thermodynamic data. See Section  15.8 for details on the items listed below.

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Gas-Phase CHEMKIN   contains parameters to import the gas phase chemkin mechanism.
Gas-Phase CHEMKIN Mechanism File   specifies the path of the Chemkin file to be read.

Gas-Phase Thermodynamic Database File   specifies the location of the thermodynamic database.

Import Surface Chemkin Mechanism   enables parameters to import the surface chemkin mechanism.

Import Transport Property Databases   (optional) allows to import transport properties.



Flamelet 3D Surfaces Panel


The Flamelet 3D Surfaces panel allows you to display 2D plots and 3D surfaces showing the variation of species fraction or temperature with the mean mixture fraction or scalar dissipation. See Section  15.11.4 for details.

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Flamelet Type   indicates the type of flamelets whose surfaces will be displayed.

Plot Variable   enables you to choose temperature or species fraction as the variable to be plotted.

Plot Type   consists of options for plot type.

3D Surface   enables plotting on 3D surfaces.

2D curve on 3D surface   enables plotting of a 2D curve on a 3D surface.

Options   consists of the following parameters:

Draw Numbers Box   enables the display of a wireframe box with the numerical limits in each coordinate direction.

Write To File   enables saving the plot data to a file.

Curve Parameters   consists of controls related to plot display.

X-Axis Function   consists of the function against which the plot variable will be displayed.

Scalar Dissipation   enables display of plot variable against the scalar dissipation function.

Mixture Fraction   enables display of plot variable against the mixture fraction.

Constant Value of Scalar Dissipation   consists of the controls to specify the type of discretization (i.e., how the flamelet data will be sliced) for the variable that is being held constant.

Slice by   consists of the controls to specify discretization.

Index   enables you to specify discretization index of the variable that is being held constant.

Value   enables you to specify the numerical value of the variable that is being held constant.

Index   consists of the controls that are displayed when you enable Index under Slice by.

Index #   displays the index number.

Min   displays the minimum of the range of integer values that you are allowed to choose from.

Max   displays the maximum of the range of integer values that you are allowed to choose from.

Value   consists of the controls that are displayed when you enable Value under Slice by.

Value   enables you to enter the numerical value of the variable that is being held constant.

Min   displays the minimum of the range of integer values that you are allowed to choose from.

Max   displays the minimum of the range of integer values that you are allowed to choose from.



Flamelet 2D Curves Panel


The Flamelet 2D Curves panel allows you to display or write 2D curves of the unsteady flamelet. See Section  15.11.4 for details.

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Options   gives you the option to plot or Write to File 2D curves.

Plot Variable   consists of a drop-down list of variables that you can plot or write.

Plot   is a available by default. When the Write to File option is enabled the Plot button changes to a Write....


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