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Chemistry Code Generation

FLINT includes a chemistry code generation tool that converts chemical mechanism files into optimized, standalone source code for reaction kinetics.

The generation process provides a Fortran chemistry source subroutine compatible with FLINT starting from a Cantera YAML mechanism. Given a mechanism name, it parses the corresponding YAML file using Cantera’s Python API and writes a Fortran module implementing the species source terms for that mechanism.

This procedure has the same objective of KinetiX.

Functionality

The script:

  • Reads a Cantera YAML mechanism (<mech>.yaml)

  • Extracts:

  • Species list

  • Reaction list
  • Stoichiometric coefficients
  • Third-body efficiencies
  • Falloff parameters (Lindemann and Troe)
  • Generates a Fortran module: 
    <mech>_mod
    containing a subroutine: 
    subroutine <mech>(roi, temp, omegadot)

The resulting subroutine:

  • Converts species densities to molar concentrations
  • Evaluates forward and backward reaction rates

  • Handles:

  • Elementary Arrhenius reactions

  • Three-body Arrhenius reactions
  • Lindemann falloff reactions
  • Troe falloff reactions
  • Computes species mass production rates

Supported Reaction Types

The following Cantera reaction types are supported:

  • Arrhenius
  • three-body-Arrhenius
  • falloff-Lindemann

  • falloff-Troe

  • Reactions are treated as reversible by default

  • To enforce irreversibility, the backward rate must be zero in the mechanism data
  • Species efficiencies default to unity if not explicitly specified

Input and Output

Input

  • YAML mechanism file: 
    <mech>.yaml
  • Command-line argument: 
    python YTF.py <mech>

Output

  • Fortran source file: 
    <mech>.f90

Generated Fortran Interface

subroutine <mech>(roi, temp, omegadot)
  real(8), intent(inout) :: roi(ns)      ! species densities [kg/m^3]
  real(8), intent(in)    :: temp         ! temperature [K]
  real(8), intent(out)   :: omegadot(ns) ! species source terms [kg/m^3/s]
end subroutine

The generated code depends on the following FLINT modules:

  • FLINT_Lib_Thermodynamic
  • FLINT_Lib_Chemistry_data
  • FLINT_Lib_Chemistry_falloff

Limitations and Caveats

  • No custom reaction ordering is implemented

  • The script assumes:

  • Consistent species ordering between FLINT and Cantera

  • Ideal-gas thermodynamics
  • The script has been lightly tested only on mechanisms already included in FLINT
  • Error handling is minimal
  • The generated code has not been formally verified for all edge cases

⚠️ Use at your own risk: this tool is intended primarily for developer use and internal mechanism generation.

Development History