[1D] Provide reasonable initial grid for ImpingingJet

doc/sphinx/cython/onedim.rst

@@ -29,7 +29,7 @@ CounterflowPremixedFlame
 
 ImpingingJet
 ^^^^^^^^^^^^
-.. autoclass:: ImpingingJet(gas, grid=None)
+.. autoclass:: ImpingingJet(gas, grid=None, width=None)
 
 Flow Domains
 ------------

interfaces/cython/cantera/examples/onedim/stagnation_flame.py

@@ -31,10 +31,8 @@ mdot = [0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12]  # kg/m^2/s
 rxnmech = 'h2o2.cti'  # reaction mechanism file
 comp = 'H2:1.8, O2:1, AR:7'  # premixed gas composition
 
-# The solution domain is chosen to be 50 cm, and a point very near the
-# downstream boundary is added to help with the zero-gradient boundary
-# condition at this boundary.
-initial_grid = np.linspace(0.0, 0.2, 12)  # m
+# The solution domain is chosen to be 20 cm
+width = 0.2 # m
 
 tol_ss = [1.0e-5, 1.0e-13]  # [rtol atol] for steady-state problem
 tol_ts = [1.0e-4, 1.0e-9]  # [rtol atol] for time stepping
@@ -56,7 +54,7 @@ gas.TPX = tburner, p, comp
 # Create the stagnation flow object with a non-reactive surface.  (To make the
 # surface reactive, supply a surface reaction mechanism. See example
 # catalytic_combustion.py for how to do this.)
-sim = ct.ImpingingJet(gas=gas, grid=initial_grid)
+sim = ct.ImpingingJet(gas=gas, width=width)
 
 # set the mass flow rate at the inlet
 sim.inlet.mdot = mdot[0]

interfaces/cython/cantera/examples/surface_chemistry/catalytic_combustion.py

@@ -30,8 +30,8 @@ comp1 = 'H2:0.05, O2:0.21, N2:0.78, AR:0.01'
 # composition of the inlet premixed gas for the methane/air case
 comp2 = 'CH4:0.095, O2:0.21, N2:0.78, AR:0.01'
 
-# the initial grid, in meters. The inlet/surface separation is 10 cm.
-initial_grid = [0.0, 0.02, 0.04, 0.06, 0.08, 0.1]  # m
+# The inlet/surface separation is 10 cm.
+width = 0.1 # m
 
 # numerical parameters
 tol_ss = [1.0e-5, 1.0e-9]  # [rtol, atol] for steady-state problem
@@ -65,7 +65,7 @@ surf_phase.advance_coverages(1.0)
 
 # create the object that simulates the stagnation flow, and specify an initial
 # grid
-sim = ct.ImpingingJet(gas=gas, grid=initial_grid, surface=surf_phase)
+sim = ct.ImpingingJet(gas=gas, width=width, surface=surf_phase)
 
 # Objects of class StagnationFlow have members that represent the gas inlet
 # ('inlet') and the surface ('surface'). Set some parameters of these objects.

interfaces/cython/cantera/onedim.py

@@ -788,13 +788,18 @@ class ImpingingJet(FlameBase):
     """An axisymmetric flow impinging on a surface at normal incidence."""
     __slots__ = ('inlet', 'flame', 'surface')
 
-    def __init__(self, gas, grid=None, surface=None):
+    def __init__(self, gas, grid=None, width=None, surface=None):
         """
         :param gas:
             `Solution` (using the IdealGas thermodynamic model) used to
             evaluate all gas properties and reaction rates.
         :param grid:
-            Array of initial grid points
+            A list of points to be used as the initial grid. Not recommended
+            unless solving only on the initial grid; Use the `width` parameter
+            instead.
+        :param width:
+            Defines a grid on the interval [0, width] with internal points
+            determined automatically by the solver.
         :param surface:
             A Kinetics object used to compute any surface reactions.
 
@@ -805,6 +810,9 @@ class ImpingingJet(FlameBase):
         self.inlet = Inlet1D(name='inlet', phase=gas)
         self.flame = AxisymmetricStagnationFlow(gas, name='flame')
 
+        if width is not None:
+            grid = np.array([0.0, 0.2, 0.4, 0.6, 0.8, 1.0]) * width
+
         if surface is None:
             self.surface = Surface1D(name='surface', phase=gas)
             self.surface.T = gas.T