Inconsistency between TROE formula and code when T** is zero. #683
Description
Cantera version
2.3.0
Operating System
Linux Ubuntu18.04 64bit
Python/MATLAB version
3.7
Expected Behavior
When T** is not given, the default value is 0.0, as description in https://cantera.org/science/reactions.html . Then the last term exp(-T**/T) ==1
Actual Behavior
When T** is not given, the last term exp(-T**/T) is ignored so this term is actually zero.
Steps to reproduce
- With a very small T**
cti_def = '''
ideal_gas(name='gas', elements='O H C',
species='gri30:H CH2 CH3 O2 H2O CO2',
reactions='all',
options=['skip_undeclared_elements', 'skip_undeclared_species', 'skip_undeclared_third_bodies'],
initial_state=state(temperature=2000, pressure=101325))
# Reaction 50
falloff_reaction( "H + CH2 (+ M) <=> CH3 (+ M)",
kf = [6.00000E+14, 0, 0],
kf0 = [1.04000E+26, -2.76, 1600],
falloff = Troe(A = 0.562, T3 = 91, T1 = 5836, T2 = 1e-10))
'''
gas = ct.Solution(source=cti_def)
gas.TPX = 2000,1e6,[1,1,1,1,1,1]
gas.net_rates_of_progress
## output array([6.57248322e+10])- Without T**
cti_def = '''
ideal_gas(name='gas', elements='O H C',
species='gri30:H CH2 CH3 O2 H2O CO2',
reactions='all',
options=['skip_undeclared_elements', 'skip_undeclared_species', 'skip_undeclared_third_bodies'],
initial_state=state(temperature=2000, pressure=101325))
# Reaction 50
falloff_reaction( "H + CH2 (+ M) <=> CH3 (+ M)",
kf = [6.00000E+14, 0, 0],
kf0 = [1.04000E+26, -2.76, 1600],
falloff = Troe(A = 0.562, T3 = 91, T1 = 5836))
'''
gas = ct.Solution(source=cti_def)
gas.TPX = 2000,1e6,[1,1,1,1,1,1]
gas.net_rates_of_progress
## output array([2.8516357e+10])Comment
According to CHEMKIN's source code and theory guide, this behavior of cantera is consistent with the implementation of CHEMKIN but it is inconsistent with the cantera's document, CHEMKIN's theory guide and Troe's paper.
However, I do not know which is correct. It may influence the behavior of Weiyao's 89 species, 683 reactions reduced mechanism for kerosene.