Flamelet Tables

Flamelet library tables are precomputed laminar flames that are parametrized by a few thermodynamic variables. Turbulent fluctuations are included in the tables.

Combustion models can lookup these tables and access data through a vector of independent variables. The tables store data independently of the combustion model which avoids a high computational cost while providing accurate results.

Each thermodynamic state of a given temperature and composition, is parametrized by mixture fraction $Z$ , enthalpy $h$ , and possibly other variables such as scalar dissipation $\chi$ and reaction progress variable $c$ .

You can create flamelet tables for each of the flamelet models within Simcenter STAR-CCM+. If you run Simcenter STAR-CCM+ in parallel, the flamelet table is generated in parallel. Each flamelet model table generator allows you to specify the chemistry definition, the composition of fluid streams, and several other parameters. You can choose to save flamelet tables in the .sim file, or in a separate location—which is useful to save disk space when using the same flamelet tables in different .sim files. The [Table Generator] > Parameters > [Numerical Settings] node contains a set of Table Dimensions, each of which provides the option to use adaptive gridding. All flamelet variables that are plotted are given in SI units, which cannot be changed—this is regardless of any preferred unit choice.

Adaptive gridding places table points such that table interpolation is accurate to a tolerance that you specify. Adaptive gridding is useful for resolving flamelet tables where the variables that are stored in the table change non-linearly. Since adaptive tables generally provide more accurate as well as smaller, tables, adaptive gridding is recommended for all table dimensions except the FGM Progress Variable Variance. For FGM Progress Varaible Variance, a single point (delta function PDF) is recommended.

When using adaptive gridding, Simcenter STAR-CCM+ starts to generate the flamelet table using an initial coarse mesh. Simcenter STAR-CCM+ then inserts a new table point midway between these existing points. If the difference between linear interpolation of the two existing points and the newly inserted point is less than the normalized tolerance, the newly inserted point is discarded. If not, the process is repeated until the maximum number of grid points are reached.

For more information about flamelet tables and adaptive gridding, see Flamelet Tables (Theory).

For instructions on how to create a flamelet table, see Creating Flamelet Tables.