Cantera/Gases

Some scattered notes on Cantera gas objects.

Specifying Thermochemical State

For a multicomponent mixture of gas containing N components, the thermochemical state of the gas can be specified by specifying N+1 thermodynamic variables.

The gas state can be specified using the set method, which takes a couple of keywords for specifying which variable you wish to set. The following parameters are mass-specific, meaning they are specified per unit mass:

• Pressure P
• Temperature T
• Specific volume V
• Mass density Rho
• Mass fractions Y
• Mole fractions X
• Enthalpy H
• Entropy S
• Internal energy U

(Note that if composition is not specified, it remains unchanged.)

These keywords can be used with the phase set method,

from Cantera import *

g = GRI30()

g.set(X="H2:1.0, CO2:3.0", T=298.15, P=OneAtm)
g.set(P=OneAtm, Rho=0.10)

Code

Python Interface

The Python interface implements the set() method as a standalone function, in the following file:

/path/to/cantera/interfaces/python/Cantera/set.py

The set() method is a wrapper function to methods that individually set thermodynamic property, like setTemperature() or setDensity(), or methods that set pairs of properties, like setState_UV() or setState_HP().

These methods, in turn, are defined in the Phase classes, which themselves utilize the C API to specify these thermodynamic properties.