16.6.1 Steady Flamelet

In the Flamelet tab of the Species Model dialog box (Figure  16.6.1), you will enter values for parameters of the flamelet(s).

Figure 16.6.1: The Species Model Dialog Box ( Flamelet Tab)

The Flamelet Parameters are as follows:

Number of Grid Points in Flamelet   specifies the number of mixture fraction grid points distributed between the oxidizer ( $f=0$) and the fuel ( $f=1$). Increased resolution will provide greater accuracy, but since the flamelet species and temperature are solved coupled and implicit in $f$ space, the solution time and memory requirements increase greatly with the number of $f$ grid points.

Maximum Number of Flamelets   specifies the maximum number of laminar flamelet profiles to be calculated. If the flamelet extinguishes before this number is reached, flamelet generation is halted and the actual number of flamelets in the flamelet library will be less than this value.

Initial Scalar Dissipation   is the scalar dissipation of the first flamelet in the library. This corresponds to $\chi_0$ in this equation in the separate Theory Guide.

Scalar Dissipation Step   specifies the interval between scalar dissipation values (in s $^{-1}$) for which multiple flamelets will be calculated. This corresponds to $\Delta \chi$ in this equation in the separate Theory Guide.

Automated Grid Refinement employs an adaptive algorithm, which inserts grid points so that the change of values, as well as the change of slopes, between successive grid points is less than user specified tolerances. For information about this option, refer to this section in the separate Theory Guide.

Initial Number of Grid Points in Flamelet   calculates a steady solution on a coarse grid, with a default of $8$. See this equation in the separate Theory Guide.

Maximum Number of Grid Points in Flamelet   has a default of $04$.

Maximum Change in Value Ratio   has a default of $0.5$ and is $\epsilon_v$ in this equation in the separate Theory Guide.

Maximum Change in Slope Ratio   has a default of $0.5$ and is $\epsilon_s$ in this equation in the separate Theory Guide.

Click Calculate Flamelets to begin the laminar flamelet calculation. Sample output for a flamelet calculation is shown below.

Generating flamelet 1 at scalar dissipation   0.01 /s

Time (s)       Temp (K)    Residual
1.679e-05      2233.7      3.779e+00
5.038e-05      2233.0      7.734e-02
1.175e-04      2231.5      1.648e-01
2.519e-04      2228.6      3.652e-01
5.206e-04      2223.6      8.295e-01
1.058e-03      2215.7      2.100e+00
2.133e-03      2205.5      3.540e+00
4.282e-03      2197.0      4.607e+00
8.581e-03      2193.6      6.639e+00
1.718e-02      2193.1      4.905e+00
3.437e-02      2193.4      5.792e+00
6.877e-02      2194.3      4.659e+00
1.375e-01      2195.3      3.922e+00
2.751e-01      2192.2      3.181e+00
5.502e-01      2188.6      2.549e+00
1.100e+00      2184.8      1.639e+00
2.201e+00      2182.9      4.604e+00
4.402e+00      2186.8      1.307e+00
8.804e+00      2189.6      4.420e-01
1.761e+01      2190.0      8.581e-02
3.522e+01      2190.0      1.199e-02
7.043e+01      2190.0      1.735e-03
1.409e+02      2190.0      4.217e-04
2.817e+02      2190.0      6.892e-05
5.635e+02      2190.0      6.777e-06

Flamelet successfully generated