[1D] Fix using non-default tolerances after automatic grid expansion

This is analogous to the issue with multicomponent transport / Soret
diffusion that was reported in #615 and fixed in #631.

interfaces/cython/cantera/onedim.pyx

@@ -1137,6 +1137,7 @@ cdef class Sim1D:
                 if isinstance(dom, _FlowBase):
                     dom.set_transport(self.gas)
 
+        # Do initial solution steps with default tolerances
         have_user_tolerances = any(dom.have_user_tolerances for dom in self.domains)
         if have_user_tolerances:
             # Save the user-specified tolerances
@@ -1145,6 +1146,14 @@ cdef class Sim1D:
             atol_ts_final = [dom.transient_abstol() for dom in self.domains]
             rtol_ts_final = [dom.transient_reltol() for dom in self.domains]
 
+        def restore_tolerances():
+            if have_user_tolerances:
+                for i in range(len(self.domains)):
+                    self.domains[i].set_steady_tolerances(abs=atol_ss_final[i],
+                                                        rel=rtol_ss_final[i])
+                    self.domains[i].set_transient_tolerances(abs=atol_ts_final[i],
+                                                            rel=rtol_ts_final[i])
+
         for dom in self.domains:
             dom.set_default_tolerances()
 
@@ -1203,6 +1212,7 @@ cdef class Sim1D:
                 # restore settings before re-raising exception
                 set_transport(transport)
                 set_soret(True)
+                restore_tolerances()
                 raise e
 
             # If initial solve using energy equation fails, fall back on the
@@ -1221,6 +1231,7 @@ cdef class Sim1D:
                     # restore settings before re-raising exception
                     set_transport(transport)
                     set_soret(True)
+                    restore_tolerances()
                     raise e
 
                 if solved:
@@ -1236,6 +1247,7 @@ cdef class Sim1D:
                         # restore settings before re-raising exception
                         set_transport(transport)
                         set_soret(True)
+                        restore_tolerances()
                         raise e
 
             if solved and not self.extinct() and refine_grid:
@@ -1251,6 +1263,7 @@ cdef class Sim1D:
                     # restore settings before re-raising exception
                     set_transport(transport)
                     set_soret(True)
+                    restore_tolerances()
                     raise e
 
                 if solved and not self.extinct():
@@ -1276,11 +1289,7 @@ cdef class Sim1D:
 
         if have_user_tolerances:
             log('Solving with user-specified tolerances')
-            for i in range(len(self.domains)):
-                self.domains[i].set_steady_tolerances(abs=atol_ss_final[i],
-                                                      rel=rtol_ss_final[i])
-                self.domains[i].set_transient_tolerances(abs=atol_ts_final[i],
-                                                         rel=rtol_ts_final[i])
+            restore_tolerances()
 
         # Final call with expensive options enabled
         if have_user_tolerances or solve_multi or soret_doms:

interfaces/cython/cantera/test/test_onedim.py

@@ -205,10 +205,12 @@ def test_auto_width2(self):
                         width=0.1)
 
         self.sim.set_refine_criteria(ratio=4, slope=0.8, curve=0.8)
+        self.sim.flame.set_steady_tolerances(T=(2e-4, 1e-8))
         self.sim.solve(refine_grid=True, auto=True, loglevel=0)
+
         self.assertNear(self.sim.velocity[0], 17.02, 1e-1)
         self.assertLess(self.sim.grid[-1], 2.0) # grid should not be too wide
-
+        self.assertEqual(self.sim.flame.tolerances("T"), (2e-4, 1e-8))
 
     @utilities.slow_test
     def test_converge_adiabatic(self):