From e0a0fa975846ab43a0286ea0bf9a043545ee8e51 Mon Sep 17 00:00:00 2001
From: Ray Speth <speth@mit.edu>
Date: Tue, 26 Jul 2022 20:47:46 -0400
Subject: [PATCH] [Python] Add equivalence_ratio to CounterflowDiffusionFlame

---
 interfaces/cython/cantera/onedim.py           | 12 ++++++++++++
 interfaces/cython/cantera/test/test_onedim.py |  6 ++++++
 2 files changed, 18 insertions(+)

diff --git a/interfaces/cython/cantera/onedim.py b/interfaces/cython/cantera/onedim.py
index 373b48615b..637d33deef 100644
--- a/interfaces/cython/cantera/onedim.py
+++ b/interfaces/cython/cantera/onedim.py
@@ -1449,6 +1449,18 @@ def mixture_fraction(self, m):
             vals[i] = self.gas.mixture_fraction(Yf, Yo, 'mass', m)
         return vals
 
+    @property
+    def equivalence_ratio(self):
+        Yf = [self.solution(k, 0) for k in self.gas.species_names]
+        Yo = [self.solution(k, self.flame.n_points-1) for k in self.gas.species_names]
+
+        vals = np.empty(self.flame.n_points)
+        for i in range(self.flame.n_points):
+            self.set_gas_state(i)
+            vals[i] = self.gas.equivalence_ratio(Yf, Yo, "mass")
+        return vals
+
+
 class ImpingingJet(FlameBase):
     """An axisymmetric flow impinging on a surface at normal incidence."""
     __slots__ = ('inlet', 'flame', 'surface')
diff --git a/interfaces/cython/cantera/test/test_onedim.py b/interfaces/cython/cantera/test/test_onedim.py
index 689d6dc299..22439cd2e3 100644
--- a/interfaces/cython/cantera/test/test_onedim.py
+++ b/interfaces/cython/cantera/test/test_onedim.py
@@ -1019,6 +1019,12 @@ def test_mixture_fraction(self):
         self.assertTrue(all(Z >= 0))
         self.assertTrue(all(Z <= 1.0))
 
+    def test_equivalence_ratio(self):
+        self.create_sim(p=ct.one_atm)
+        phi = self.sim.equivalence_ratio
+        assert phi[0] == np.inf
+        assert np.isclose(phi[-1], 0.0)
+
 class TestCounterflowPremixedFlame(utilities.CanteraTest):
     # Note: to re-create the reference file:
     # (1) set PYTHONPATH to build/python.