CERFACS Chemistry Sharing knowledge for CFD chemical kinetics

⚙️ What is PACMIND-SA?

PACMIND-SA is a phenomenological model for Plasma-Assisted Combustion (PAC). A phenomenological model for PAC is a simplified, physics-informed representation of the key processes that govern the interaction between plasma discharges and combustion chemistry. Instead of resolving every microscopic detail, these models focus on capturing the dominant mechanisms—such as radical generation, energy deposition, and ignition enhancement—using compact mathematical expressions or reduced-order kinetics.

To reference the PACMIND-SA model, please refer to H. Gillingham et al, “A Semi-Analytical model for Plasma-Assisted Combustion: Application to NH3-H2-air mixtures”, Combustion and Flame, Vol. 283, 2026.

🔍 How to use PACMIND-SA model?

We provide ready-to-use executable scripts that allow users to directly compute the model parameters for any given thermochemical state. Our goal is to make the model immediately accessible: with only a simple input text file, readers can run the executable and obtain the parameters without any additional setup. In the near future, this tool will also be released as a fully open-source project with a dedicated GitHub repository.

Windows, MacOS and Linux version are available here.

The executable requires as input a plain text file containing 8 values in the following order:

1.	Reduced electric field (Td)
2.	Temperature (K)
3.	Pressure (Pa)
4.	Mole fraction of N2
5.	Mole fraction of O2
6.	Mole fraction of NH3
7.	Mole fraction of H2
8.	Mole fraction of H2O

The values may be provided on one or several lines. Comments can be added after any line using !, #, or //. An example input file is distributed with the executable and looks like:

250         ! Reduced electric field (Td)
300         ! Gas temperature (K)
101325      ! Pressure (Pa)
0.617       ! Mole fraction N2
0.164       ! Mole fraction O2 
0.219       ! Mole fraction NH3 
0.000       ! Mole fraction H2
0.000       ! Mole fraction H2O

The executable automatically checks input consistency:

• Negative values for the reduced electric field, temperature, or pressure will generate a warning, and no output will be produced.
• Negative mole fractions are reset to zero.
• If the mole fractions do not sum to unity (within a tolerance of 10-8), they are automatically renormalized.

To run the code, simply select the executable matching your operating system and, in a terminal opened in the same directory, type:

./pacmind_sa input.txt

The program will then generate an output file named output_coefficients.txt containing the 14 PACMIND-SA coefficients (fast gas heating, vibrational excitation, and the 12 chemical processes), along with a record of the input parameters used.

If you encounter a “permission denied” error when running the executable, grant execution rights with:

chmod +x pacmind_sa

If you encounter any issue, please feel free to contact: barleon@cerfacs.fr