Difference in Laminar flamespeed value from v2.5.0 to v3.1.0 or v3.2.0

[vijay...@gmail.com]

Flamespeeds from v2.5.0 and v3.1.0 are differing slightly. Even v3.2.0 is showing the difference. It is minor but I would like to check if anyone else has noticed this too or, have a reason for it. I ran the script below in both versions and the results are as below:

Cantera version: 3.1.0
mixture-averaged flamespeed = 0.705816 m/s

Cantera version: 2.5.1
mixture-averaged flamespeed = 0.711264 m/s

Script:

import cantera as ct

# Simulation parameters
p = ct.one_atm # pressure [Pa]
Tin = 300.0 # unburned gas temperature [K]
reactants = 'H2:1.1, O2:1, AR:5' # premixed gas composition
width = 0.03 # m
loglevel = 1 # amount of diagnostic output (0 to 8)

# Solution object used to compute mixture properties, set to the state of the
# upstream fuel-air mixture
gas = ct.Solution('h2o2.yaml')
gas.TPX = Tin, p, reactants

# Set up flame object
f = ct.FreeFlame(gas, width=width)
f.set_refine_criteria(ratio=3, slope=0.06, curve=0.12)

# Solve with mixture-averaged transport model
f.transport_model = 'Mix'
f.solve(loglevel=loglevel, auto=True)

print('Cantera version:',ct.__version__)
print(f"mixture-averaged flamespeed = {f.velocity[0]:7f} m/s")

[Ray Speth]

Hi,

I believe what you’re seeing is a result of a change in how the mixture-averaged diffusion fluxes are calculated. This was discussed in Enhancement #187 and implemented in PR #1626. It is also listed (briefly) in the Changelog for Cantera 3.1.0.

Regards,
Ray

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[vijay...@gmail.com]

Thank you Ray for pointing to the enhancement discussion.