addresses issue #615

interfaces/cython/cantera/onedim.pyx

@@ -881,6 +881,12 @@ cdef class Sim1D:
             self.sim.solve(loglevel, <cbool>refine_grid)
             return
 
+        def set_transport(multi):
+            self.gas.transport_model = multi
+            for dom in self.domains:
+                if isinstance(dom, _FlowBase):
+                    dom.set_transport(self.gas)
+
         have_user_tolerances = any(dom.have_user_tolerances for dom in self.domains)
         if have_user_tolerances:
             # Save the user-specified tolerances
@@ -894,16 +900,18 @@ cdef class Sim1D:
 
         # Do initial steps without Soret diffusion
         soret_doms = [dom for dom in self.domains if getattr(dom, 'soret_enabled', False)]
-        for dom in soret_doms:
-            dom.soret_enabled = False
+
+        def set_soret(soret):
+            for dom in soret_doms:
+                dom.soret_enabled = soret
+
+        set_soret(False)
 
         # Do initial solution steps without multicomponent transport
+        transport = self.gas.transport_model
         solve_multi = self.gas.transport_model == 'Multi'
         if solve_multi:
-            self.gas.transport_model = 'Mix'
-            for dom in self.domains:
-                if isinstance(dom, _FlowBase):
-                    dom.set_transport(self.gas)
+            set_transport('Mix')
 
         def log(msg, *args):
             if loglevel:
@@ -934,6 +942,11 @@ cdef class Sim1D:
             except CanteraError as e:
                 log(str(e))
                 solved = False
+            except Exception as e:
+                # restore settings before re-raising exception
+                set_transport(transport)
+                set_soret(True)
+                raise e
 
             # If initial solve using energy equation fails, fall back on the
             # traditional fixed temperature solve followed by solving the energy
@@ -947,6 +960,11 @@ cdef class Sim1D:
                 except CanteraError as e:
                     log(str(e))
                     solved = False
+                except Exception as e:
+                    # restore settings before re-raising exception
+                    set_transport(transport)
+                    set_soret(True)
+                    raise e
 
                 if solved:
                     log('Solving on {} point grid with energy equation re-enabled', N)
@@ -957,6 +975,11 @@ cdef class Sim1D:
                     except CanteraError as e:
                         log(str(e))
                         solved = False
+                    except Exception as e:
+                        # restore settings before re-raising exception
+                        set_transport(transport)
+                        set_soret(True)
+                        raise e
 
             if solved and not self.extinct() and refine_grid:
                 # Found a non-extinct solution on the fixed grid
@@ -967,6 +990,11 @@ cdef class Sim1D:
                 except CanteraError as e:
                     log(str(e))
                     solved = False
+                except Exception as e:
+                    # restore settings before re-raising exception
+                    set_transport(transport)
+                    set_soret(True)
+                    raise e
 
                 if solved and not self.extinct():
                     # Found a non-extinct solution on the refined grid
@@ -983,15 +1011,11 @@ cdef class Sim1D:
 
         if solve_multi:
             log('Solving with multicomponent transport')
-            self.gas.transport_model = 'Multi'
-            for dom in self.domains:
-                if isinstance(dom, _FlowBase):
-                    dom.set_transport(self.gas)
+            set_transport('Multi')
 
         if soret_doms:
             log('Solving with Soret diffusion')
-            for dom in soret_doms:
-                dom.soret_enabled = True
+            set_soret(True)
 
         if have_user_tolerances:
             log('Solving with user-specifed tolerances')
@@ -1005,7 +1029,6 @@ cdef class Sim1D:
         if have_user_tolerances or solve_multi or soret_doms:
             self.sim.solve(loglevel, <cbool>refine_grid)
 
-
     def refine(self, loglevel=1):
         """
         Refine the grid, adding points where solution is not adequately