CTI = CanTera Input file

CTI files use a custom markup language to specify information about the kinetics.

A CTI file must specify information about three things:

Division of CTI Files

The file can be divided into multiple parts:

Phase specification
Species
- Gas species
- Surface species
Reactions
- Gas reactions
- Surface reactions

Units Specification

The units are the first thing defined in the file:

units(length = "cm", time = "s", quantity = "mol", act_energy = "J/mol")

Phases

Information about specifying phases in Cantera input file here: Cantera/CTI Files/Phases

Species

Information about specifying species in Cantera input files here: Cantera/CTI Files/Species

Reactions

Information about specifying reactions in Cantera input files here: Cantera/CTI Files/Reactions

CTI Code

Conversion of Chemkin Files to CTI

CTI files can be generated from the ck2cti app, contained in cantera/src/apps/ck2cti.cpp, which is a command-line utility to turn Chemkin-II reaction mechanism files, as well as transport and thermodynamic database files, into a CTI file.

This utility can be called like this:

ck2cti -i input -t thermo -tr transport -id idtag

where "input" is a Chemkin II reaction mechanism file (the meat of the CTI file), "thermo" is a file in which to look for thermodynamic data if there is no THERMO section of the Chemkin input file, "transport" is a file in which to look for transport data (no transport data is put into the final CTI file if this is left off), and "idtag" is a string name to give to the phase created in the new CTI file.

Conversion of CTI to XML

Once you have a CTI file (generated by hand, from a modified example, or from a Chemkin input file), the CTI file is then turned into an XML file, which is ultimately the format used by Cantera. This conversion is performed by the ct2ctml app, which is in cantera/src/base/ct2ctml.cpp. This code, in turn, creates a direct call from C++ to Python.

In ct2ctml.cpp, the following code block illustrates the call to Python to convert a CTI file to an XML file:

    try {
        exec_stream_t python;
        python.set_wait_timeout(exec_stream_t::s_all, 1800000); // 30 minutes
        python.start(pypath(), "-i");
        stringstream output_stream;
        python.in() <<
            "if True:\n" << // Use this so that the rest is a single block
            "    import sys\n" <<
            "    sys.stderr = sys.stdout\n" <<
            "    import ctml_writer\n" <<
            "    ctml_writer.convert(r'" << file << "')\n" <<
            "    sys.exit(0)\n\n"
            "sys.exit(7)\n";
        python.close_in();
        std::string line;
        while (python.out().good()) {
            std::getline(python.out(), line);
            output_stream << line << std::endl;;
        }
        python.close();
        python_exit_code = python.exit_code();
        python_output = stripws(output_stream.str());
    } catch (std::exception& err) {

The code that deals with CTI files is actually in two lines of Python code:

import ctml_writer
ctml_writer.convert( [file] )

The call to ctml_writer references the Python routines located in cantera/interfaces/python/ctml_writer.py, which interprets the CTI file and turns it into an XML file.

Looking through the ctml_writer.py code, you can see that it starts at the convert() method, then moves to the write() method, where it builds each piece of information specified in the CTI into an XML data structure, which is then written to a file.

Cantera/CTI Files

From charlesreid1

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