[Python/1D] Detect invalid boundary conditions for flame configurations

Fixes Cantera#1694

interfaces/cython/cantera/onedim.py

@@ -929,6 +929,10 @@ def set_initial_guess(self, data=None, group=None):
         u0o = mdoto / rho0o
         T0o = self.oxidizer_inlet.T
 
+        if mdoto == mdotf == 0.0:
+            raise CanteraError("Mass flow for fuel and/or oxidizer "
+                               "must be positive")
+
         zst = 1 / (1 + self.gas.stoich_air_fuel_ratio(Yin_f, Yin_o, 'mass'))
         Yst = zst * Yin_f + (1.0 - zst) * Yin_o
 
@@ -1348,6 +1352,10 @@ def set_initial_guess(self, equilibrate=True, data=None, group=None):
         rhob = self.gas.density
         ub = self.products.mdot / rhob
 
+        if uu == ub == 0.0:
+            raise CanteraError("Mass flow for reactants and/or products "
+                               "must be positive")
+
         locs = np.array([0.0, 0.4, 0.6, 1.0])
         self.set_profile('T', locs, [Tu, Tu, Teq, Tb])
         for k in range(self.gas.n_species):
@@ -1422,6 +1430,9 @@ def set_initial_guess(self, data=None, group=None):
         if data:
             return
 
+        if self.reactants.mdot == 0:
+            raise CanteraError("Reactants velocity must be positive")
+
         Yu = self.reactants.Y
         Tu = self.reactants.T
         self.gas.TPY = Tu, self.flame.P, Yu

test/python/test_onedim.py

@@ -1152,6 +1152,27 @@ def test_equivalence_ratio(self):
         assert phi[0] == np.inf
         assert np.isclose(phi[-1], 0.0)
 
+    def test_bad_boundary_conditions(self):
+        gas = ct.Solution("h2o2.yaml")
+        gas.TP = 300, ct.one_atm
+        sim = ct.CounterflowDiffusionFlame(gas, width=0.2)
+        sim.fuel_inlet.X = "H2: 1.0"
+
+        sim.oxidizer_inlet.X = "H2: 1.0, O2: 1.0"
+        sim.fuel_inlet.X = "O2: 1.0, N2: 3.76"
+        with pytest.raises(ct.CanteraError, match="Mass flow for fuel"):
+            sim.set_initial_guess()
+
+        sim.fuel_inlet.mdot = 1.0
+        sim.oxidizer_inlet.mdot = 1.0
+        with pytest.raises(ct.CanteraError, match="too much oxygen"):
+            sim.set_initial_guess()
+
+        sim.oxidizer_inlet.X = "O2: 1.0, N2: 3.76"
+        sim.fuel_inlet.X = "H2: 1.0"
+        sim.set_initial_guess()
+
+
 class TestCounterflowPremixedFlame(utilities.CanteraTest):
     # Note: to re-create the reference file:
     # (1) set PYTHONPATH to build/python.
@@ -1262,6 +1283,14 @@ def test_restart(self):
         self.assertNear(mdot[0], sim.reactants.mdot, 1e-4)
         self.assertNear(mdot[-1], -sim.products.mdot, 1e-4)
 
+    def test_bad_boundary_conditions(self):
+        gas = ct.Solution("h2o2.yaml")
+        gas.TPX = 300, 0.05 * ct.one_atm, "H2:1.6, O2:1, AR:7"
+        sim = ct.CounterflowPremixedFlame(gas=gas, width=0.2)
+        with pytest.raises(ct.CanteraError, match="must be positive"):
+            sim.solve(loglevel=0)
+
+
 class TestCounterflowPremixedFlameNonIdeal(utilities.CanteraTest):
     # Note: to re-create the reference file:
     # (1) set PYTHONPATH to build/python.
@@ -1700,6 +1729,12 @@ def run_save_restore(self, mode):
 
         sim2.solve(loglevel=0)
 
+    def test_bad_boundary_conditions(self):
+        gas = ct.Solution("h2o2.yaml")
+        gas.TPX = 300, 0.05 * ct.one_atm, "H2:1.6, O2:1, AR:7"
+        sim = ct.CounterflowTwinPremixedFlame(gas=gas, width=0.2)
+        with pytest.raises(ct.CanteraError, match="must be positive"):
+            sim.solve(loglevel=0)
 
 class TestIonFreeFlame(utilities.CanteraTest):
     @utilities.slow_test