RFS (Robust Flamelet Solver)

Counterflow diffusion flames are a canonical problem in combustion simulations. Solutions to these systems of equations are used to perform large-scale calculations in a faster manner through tabulation.

RFS is a mixture-fraction space based flamelet solver with robust arc-length continuation and Flamelet Progress Variable (FPV) tabulation capabilities.

Features

• Robust Continuation: Mixture-fraction space solver with logarithmic arc-length continuation for quick traversal of the S-curve (from stable burning to extinction).
• FPV Tabulation: Build Flamelet Progress Variable (FPV) tables for temperature, mass fractions, and reaction source terms.
• Visualization: Tools for plotting S-curves and 2D FPV table visualizations.

Installation

1. Use conda to setup Cantera 3.0 as suggested on its website.
2. Install the dependencies:

   pip install -r requirements.txt
   

3. Make sure you have pacopy_cython available in the root directory. Request here if required.
4. Build the Cython extensions for the continuation solver:

   cd pacopy_cython
   python setup.py build_ext --inplace
   cd ..
   

Usage

Run the main simulation and tabulation script:

python main.py

Testing

To run the Bratu problem test for the continuation solver:

PYTHONPATH=. python pacopy_cython/test/test_bratu.py

Basic Example

The following snippet (simplified from main.py) illustrates how to define a problem, run continuation, and build a table:

from flamelet_problem import FlameletProblem
from tabulation_module import FPVTabulation, PV_H2O

# 1. Define the problem (Hydrogen flame at 250 PSI)
problem = FlameletProblem(
    lmbda0=8.3,
    npts=30,
    t_ox=750.0,
    t_f=290.0,
    p=1.72e6, # 250 PSI in Pa
    mech='burke-hydrogen.yaml'
)

# 2. Run arc-length continuation
problem.continuation(
    newton_tol=1.0e-3,
    max_newton_steps=40,
    stepsize0=1.0e-1,
    adaptive_theta=True
)

# 3. Build and save FPV table
tabulation = FPVTabulation(problem, pv_definition=PV_H2O)
tabulation.build_table(n_c=100)
tabulation.save_to_file('output/fpv_table.npz')

Post-Processing

Visualize the generated tables and source terms using:

python post_process.py

Whom to contact?

Please direct your queries to gpavanb1.

Acknowledgements

This would not have been possible without the immense efforts of Spitfire and Pacopy. RFS uses a Cython-optimized version of Pacopy. The sample Hydrogen mechanism is from Spitfire.