CEPTR: Chemistry Evaluation for Pele Through Recasting¶

We use CEPTR to generate C++ mechanism files from Cantera yaml chemistry files. CEPTR is a python package part of the PelePhysics source code.

Software requirements¶

The CEPTR package uses poetry to manage the Python dependencies. Poetry is therefore required to use CEPTR and can typically be installed through system package managers (e.g. HomeBrew) or following the instructions in poetry’s documentation.

To install CEPTR dependencies:

$ cd ${PELE_PHYSICS_HOME}/Support/ceptr
$ poetry update

Usage¶

There are three ways to use CEPTR to generate C++ mechanism files for a given chemistry

Using CEPTR directly:

$ cd ${PELE_PHYSICS_HOME}/Support/ceptr
$ poetry run convert -f ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/LiDryer/mechanism.yaml

Using a helper script in the directory containing the mechanism.yaml file:
```
$ ./convert.sh
```

Using a helper script in the Models directory:

$ bash ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/converter.sh -f ./LiDryer/mechanism.yaml

For non-reduced chemistries, CEPTR can take a file with a list of mechanism.yaml files to convert:

$ cd ${PELE_PHYSICS_HOME}/Support/ceptr
$ poetry run convert -l ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/list_mech

For reduced chemistries, CEPTR can take a file with a list of qssa.yaml and qssa_input.toml to convert:

$ cd ${PELE_PHYSICS_HOME}/Support/ceptr
$ poetry run convert -lq ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/list_qss_mech

For generating qssa.yaml for reduced chemistries, CEPTR can take a file with a list of skeletal.yaml and non_qssa_list.yaml:

$ cd ${PELE_PHYSICS_HOME}/Support/ceptr
$ poetry run qssa -lq ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/list_qss_mech

To generate all mechanisms:

$ poetry run convert -l ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/list_mech
$ poetry run qssa -lq ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/list_qss_mech
$ poetry run convert -lq ${PELE_PHYSICS_HOME}/Support/Mechanism/Models/list_qss_mech

Converting CHEMKIN files¶

We rely on Cantera’s ck2yaml utility to convert CHEMKIN files to the Cantera yaml format (and proceed as above with CEPTR on the resulting yaml file):

$ cd ${PELE_PHYSICS_HOME}/Support/ceptr
$ poetry run ck2yaml --input=${PATH_TO_CHEMKIN_DIR}/mechanism.inp --thermo=${PATH_TO_CHEMKIN_DIR}/therm.dat --transport=${PATH_TO_CHEMKIN_DIR}/tran.dat --permissive

The files tran.dat and therm.dat are optional if already included in the .inp file.

Generating a QSS chemistry file¶

To generate a QSS chemistry yaml file from another yaml file, one executes:

$ poetry run qssa -f ${PATH_TO_YAML}/skeletal.yaml -n ${PATH_TO_YAML}/non_qssa_list.yaml

The full list of options is:

$ poetry run qssa -h
usage: qssa [-h] -f FNAME -n NQSSA [-m {0,1,2}] [-v]

Mechanism converter

optional arguments:
  -h, --help            show this help message and exit
  -f FNAME, --fname FNAME
                        Mechanism file
  -n NQSSA, --nqssa NQSSA
                        Non-QSSA species list
  -m {0,1,2}, --method {0,1,2}
                        QSSA method (default: 2)
  -v, --visualize       Visualize quadratic coupling and QSSA dependencies

For a detailed description of these options and a further information on the way QSS mechanism are treated in CEPTR the reader may consult the QSS section.

See Tutorials (Generating NC12H26 QSS mechanism with analytical jacobian and Generating NC12H26 QSS mechanism without analytical jacobian) for generating QSS mechanisms from the .yaml files.