Enthalpy non-conservation in post-flame region

[speth]

Running with c0ed397, the following configuration:

from ember import *
import cantera as ct

# params
phi = 2.0
mech = "h2o2.yaml"
fuel = "H2:1.0"
oxid = "N2:3.76, O2:1.0"

T0 = 300
p = ct.one_atm
npoints_ini = 100

output = f"./run/phi{phi * 10}b"

conf = Config(
    Paths(
        outputDir=output,
    ),
    Chemistry(mechanismFile=mech),
    General(
        flameGeometry="cylindrical",
        unburnedLeft=False,
        fixedLeftLocation=True,
        nThreads=4,
    ),
    InitialCondition(
        fuel=fuel,
        oxidizer=oxid,
        pressure=p,
        Tu=T0,
        equivalenceRatio=phi,
        xLeft=0.0,
        xRight=0.005,
        nPoints=npoints_ini,
    ),
    StrainParameters(initial=0.0, final=0.0),
    TerminationCondition(tEnd=0.025, measurement="dTdt"),
    Times(globalTimestep=1e-6, profileStepInterval=100, regridStepInterval=2),
    Grid(rmTol=0.8, vtol=0.1, dvtol=0.16, uniformityTol=3.5),
    Debug(adaptation=False, regridding=False),
    OutputFiles(fileExtension="h5"),
)

# simulation
if __name__ == "__main__":
    conf.run()

Demonstrates some issues with conserving enthalpy in the post-flame region, which can be seen by superadiabatic temperatures that persist even as the flame's curvature decreases:

import cantera as ct
import ember
from pathlib import Path
import matplotlib.pyplot as plt

gas = ct.Solution('h2o2.yaml')
Pb = [ember.utils.load(str(pth)) for pth in Path('run/phi20b').glob('prof*.h5')]
Pb = sorted(Pb, key=lambda p: p.t)

fig, ax = plt.subplots()
for prof in Pb[::20]:
    states = ct.SolutionArray(gas, len(prof.x))
    states.TPY = prof.T, ct.one_atm, prof.Y.T
    ax.plot(prof.x, states.enthalpy_mass, label=f't = {prof.t*1000:.4} ms')