Creating CounterflowPremixedFlame, CounterflowDiffusionFlame, CounterflowTwinPremixedFlame, or CounterflowPremixedFlame objects and attempting to solve them without setting appropriate boundary conditions leads to error messages that are difficult to interpret. I think this problem could be detected while generating initial guesses and used to provide more helpful error messages.
Steps to reproduce
For CounterflowPremixedFlame
import cantera as ct
gas = ct.Solution('h2o2.yaml')
gas.TP = 300, ct.one_atm
gas.set_equivalence_ratio(0.6, 'H2:1.0', 'O2:1.0, N2:3.76')
f = ct.CounterflowPremixedFlame(gas, width=0.03)
f.solve(loglevel=1, auto=True)
This starts by generating the output:
************ Solving on 5 point grid with energy equation enabled ************
..............................................................................
Attempt Newton solution of steady-state problem...
*******************************************************************************
CanteraError thrown by Phase::setTemperature:
temperature must be positive. T = nan
*******************************************************************************
******** Initial solve failed; Retrying with energy equation disabled ********
followed by many additional failures while trying different grids, ultimately raising the exception
RuntimeWarning: invalid value encountered in scalar divide
x0 = rhou*uu * dz / (rhou*uu + rhob*ub)
---------------------------------------------------------------------------
CanteraError Traceback (most recent call last)
Cell In[5], line 9
6 gas.set_equivalence_ratio(0.6, 'H2:1.0', 'O2:1.0, N2:3.76')
8 f = ct.CounterflowPremixedFlame(gas, width=0.03)
----> 9 f.solve(loglevel=1, auto=True)
File cantera/_onedim.pyx, in cantera._onedim.Sim1D.solve()
CanteraError: Could not find a solution for the 1D problem
For CounterflowDiffusionFlame
import cantera as ct
gas = ct.Solution('h2o2.yaml')
gas.TP = 300, ct.one_atm
gas.set_equivalence_ratio(0.6, 'H2:1.0', 'O2:1.0, N2:3.76')
f = ct.CounterflowDiffusionFlame(gas, width=0.03)
f.solve(loglevel=1, auto=True)
Generates the error:
---------------------------------------------------------------------------
ZeroDivisionError Traceback (most recent call last)
Cell In[3], line 8
5 gas.set_equivalence_ratio(0.6, 'H2:1.0', 'O2:1.0, N2:3.76')
7 f = ct.CounterflowDiffusionFlame(gas, width=0.03)
----> 8 f.solve(loglevel=1, auto=True)
File cantera/onedim.py:1015, in CounterflowDiffusionFlame.solve(self, loglevel, refine_grid, auto, stage)
1010 warnings.warn(
1011 "The 'ionized-gas' transport model is untested for "
1012 "'CounterflowDiffusionFlame' objects.", UserWarning)
1013 self.flame.solving_stage = stage
-> 1015 super().solve(loglevel, refine_grid, auto)
1016 # Do some checks if loglevel is set
1017 if loglevel > 0:
File cantera/_onedim.pyx:1097, in cantera._onedim.Sim1D.solve()
File cantera/onedim.py:941, in CounterflowDiffusionFlame.set_initial_guess(self, data, group)
938 if 'H' in self.gas.element_names:
939 sOx -= 0.5 * moles('H')
--> 941 zst = 1.0 / (1 - sFuel / sOx)
942 Yst = zst * Yin_f + (1.0 - zst) * Yin_o
944 # get adiabatic flame temperature and composition
ZeroDivisionError: float division by zero
For CounterflowTwinPremixedFlame:
import cantera as ct
gas = ct.Solution('h2o2.yaml')
gas.TPX = 300, ct.one_atm, 'H2:1.0'
f = ct.CounterflowTwinPremixedFlame(gas, width=0.03)
f.solve(loglevel=1, auto=True)
Generates output that starts with
************ Solving on 7 point grid with energy equation enabled ************
..............................................................................
Attempt Newton solution of steady-state problem... failure.
Take 10 timesteps 0.0005767 -11.22
Attempt Newton solution of steady-state problem...
*******************************************************************************
CanteraError thrown by Phase::setDensity:
density must be positive. density = -818939.2759868323
*******************************************************************************
******** Initial solve failed; Retrying with energy equation disabled ********
and ultimately failing with the exception:
CanteraError Traceback (most recent call last)
Cell In[13], line 9
6 #gas.set_equivalence_ratio(0.0, 'H2:1.0', 'O2:0.0, N2:3.76')
8 f = ct.CounterflowTwinPremixedFlame(gas, width=0.03)
----> 9 f.solve(loglevel=1, auto=True)
File cantera/_onedim.pyx:1181, in cantera._onedim.Sim1D.solve()
CanteraError: Could not find a solution for the 1D problem
For CounterflowPremixedFlame:
import cantera as ct
gas = ct.Solution('h2o2.yaml')
gas.TP = 300, ct.one_atm
gas.set_equivalence_ratio(0.5, 'H2:1.0', 'O2:1.0, N2:3.76')
f = ct.CounterflowPremixedFlame(gas, width=0.03)
f.solve(loglevel=1, auto=True)
Starts by generating the output:
************ Solving on 5 point grid with energy equation enabled ************
..............................................................................
Attempt Newton solution of steady-state problem...
*******************************************************************************
CanteraError thrown by Phase::setTemperature:
temperature must be positive. T = nan
*******************************************************************************
******** Initial solve failed; Retrying with energy equation disabled ********
and ultimately failing with the exception:
CanteraError Traceback (most recent call last)
Cell In[16], line 7
5 gas.set_equivalence_ratio(0.5, 'H2:1.0', 'O2:1.0, N2:3.76')
6 f = ct.CounterflowPremixedFlame(gas, width=0.03)
----> 7 f.solve(loglevel=1, auto=True)
File cantera/_onedim.pyx:1181, in cantera._onedim.Sim1D.solve()
CanteraError: Could not find a solution for the 1D problem
Problem description
Creating
CounterflowPremixedFlame,CounterflowDiffusionFlame,CounterflowTwinPremixedFlame, orCounterflowPremixedFlameobjects and attempting to solve them without setting appropriate boundary conditions leads to error messages that are difficult to interpret. I think this problem could be detected while generating initial guesses and used to provide more helpful error messages.Steps to reproduce
For
CounterflowPremixedFlameThis starts by generating the output:
followed by many additional failures while trying different grids, ultimately raising the exception
For
CounterflowDiffusionFlameGenerates the error:
For
CounterflowTwinPremixedFlame:Generates output that starts with
and ultimately failing with the exception:
For
CounterflowPremixedFlame:Starts by generating the output:
and ultimately failing with the exception:
System information
mainat d37a76bf6Additional context
Based on a question from the Users' Group: https://groups.google.com/g/cantera-users/c/XrjpRh47coY