5.
Define the chemical boundary species to be considered for the streams in the reacting system model. Note that this step is not relevant in the case of flamelet import (Figure
15.6.3).
Figure 15.6.3: Defining Chemical Boundary Species
6.
(steady and unsteady laminar flamelet model only) If you are generating flamelets, compute the flamelet state relationships of species mass fractions, density, and temperature as a function of mixture fraction and scalar dissipation (Figure
15.6.4). For unsteady laminar flamelets, you will initialize the unsteady flamelet probability (Figure
15.11.2).
Figure 15.6.4: Calculating Steady Flamelets
7.
Compute the final chemistry look-up table, containing mean values of species fractions, density, and temperature as a function of mean mixture fraction, mixture fraction variance, and possibly enthalpy and scalar dissipation. The contents of this look-up table will reflect your preceding inputs describing the turbulent reacting system (Figure
15.6.5).
Figure 15.6.5: Calculating the Chemistry Look-Up Table
The look-up table is the stored result of the integration of Equations
15.2-16 (or
15.2-24) and
15.2-18. The look-up table will be used in
FLUENT to determine mean species mass fractions, density, and temperature from the values of mean mixture fraction (
), mixture fraction variance (
), and possibly mean enthalpy (
) and mean scalar dissipation (
) as they are computed during the
FLUENT calculation of the reacting flow. See Section
15.2.4 and Figures
15.2.8 and
15.2.10.
For a problem that includes a secondary stream (and, therefore, a second mixture fraction), you will perform the first two steps listed above for the single-mixture-fraction approach and then prepare a look-up table of instantaneous properties using Equation
15.2-12 or
15.2-14.