Flamelet Workflow

Follow the steps in this workflow to simulate single phase or VOF Multiphase (VOF) intraphase combustion using the flamelet models that are provided in Simcenter STAR-CCM+.

The steps in this workflow are intended to follow on from the initial steps in the Reacting Flow General Workflow.
  1. For the physics continuum or Eulerian VOF phase that represents the reacting flow, select the following models—in addition to the models that are previously selected, with Auto-Select recommended models activated:
    Group Box Model
    Reacting Flow Models Flamelet
    Flamelet Models
    • For perfectly-premixed and partially-premixed flames, the Flamelet Generated Manifold (FGM) model is recommended.
    • For non-premixed flames, the Steady Laminar Flamelet model is recommended.
    • If no chemical mechanism is available, use the Chemical Equilibrium model.
    Progress Variable Source (for FGM)
    • FGM Kinetic Rate
    • Coherent Flame Model (CFM).
    • Turbulent Flame Speed Closure (TFC).
    Flame Type (for Chemical Equilibrium or Steady Laminar Flamelet)
    • Non-Premixed Flame
    • Partially-Premixed Flame
    Flame Propagation (required for partially-premixed flames)
    • Coherent Flame Model (CFM).
    • Turbulent Flame Speed Closure (TFC).
  2. Select any Optional models.
    For example:
    • NOx Emission or Soot Emissions—to model the formation of these pollutants.
    • Inert Stream—allows the simulation to model an inert (chemically inactive) stream in addition to the flamelet fuel and oxidizer streams. This model allows you to define the inert stream species outside of the flamelet table, which avoids unnecessary computation of inactive species in the flamelet generation and tabulation. Useful when simulating exhaust gas recirculation (EGR) in internal combustion engines (ICE), and steam injection in gas-turbines.
    • The Radiation model is useful for modeling applications in which radiative heat transfer is important—as is the case for most combustion systems—such as in glass furnaces and in gas turbines. The soot emission models influence the Participating Media Radiation (DOM) and Gray Thermal Radiation models by contributing to the absorption coefficient of the continuous phase (the absorption coefficient describing both absorption and emission).
    • Gravity—if gravity forces significantly influence the solution, such as in fire simulations.
  3. When the model selection process is complete, you then define the flamelet table. Choose one of the following options:
    Using ASCII files. You can import the chemistry definition in standard Chemkin format—using ASCII files, and then have Simcenter STAR-CCM+ generate the flamelet tables directly.

    See Creating Flamelet Tables.
    Using a DARS library. Alternatively, if you have a FGM or SLF library, you can import it into Simcenter STAR-CCM+ and construct the table.

    See Loading Library Tables.
    NoteIf required, you can automate the flamelet table generation using the Simulation Operations feature. See Run Flamelet Table Generator.
When the flamelet table generation is complete, you then define any properties that are required for the physics models that you are using.
  1. Set the properties of any [continuum] > Models or [phase] > Models, and model sub-nodes, as required.
    NoteIt is possible to specify several combustion model constants as parameters. See Global Parameters.
    For example, if you are using the CFM or TFC models, make sure that all necessary reaction constants are specified.
    • If you are using the Flamelet Generated Manifold (FGM) model, select the Flamelet Generated Manifold (FGM) > Progress Variable Variance node and set the method for solving the progress variable variance. See: Flamelet Generated Manifold Model Reference.
    • If you are using the Steady Laminar Flamelet model, by default, the Steady Laminar Flamelet model selects the Ideal Gas model and the Non-Adiabatic model—which is necessary even for insignificant heat losses/gains.
    • For the CFM model, set the following properties under the Coherent Flame Model (CFM) node.
      • CFM Constant, Alpha, α in Eqn. (3562).
      • CFM Constant, Beta, β , in Eqn. (3562).
      • CFM Constant, A, the flame surface annihilation coefficient, A .
      • CFM Constant, B, the flame quenching coefficient by stretch, B .
    • For the TFC model, set the TFC Rate Coefficient, A constant, A in Eqn. (3556), under the Turbulent Flame Speed Closure (TFC) > TFC Rate Coefficient, A node.
  2. Return to the Reacting Flow General Workflow.