added method molarFluxes

Cantera/python/Cantera/Transport.py

@@ -1,20 +1,22 @@
-""" Cantera provides a set of classes for 'transport managers' that
-manage the computation of various transport properties of a phase of
-matter. Every object representing a phase of matter for which
-transport properties are needed has a transport manager assigned to
-it. The transport manager has only one job: to compute the values of
-the transport properties of its assigned phase.
+""" Cantera provides a set of 'transport manager' classes that manage
+the computation of transport properties. Every object representing a
+phase of matter for which transport properties are needed has a
+transport manager assigned to it. The transport manager has only one
+job: to compute the values of the transport properties of its assigned
+phase.
 
-A transport manager may do additional things not apparent to the user
-in order to improve the speed of transport property evaluation. For
-example, it may cache intermediate results that depend only on
-temperature, so that if it happens to be called again at the same
-temperature (a common occurrence) it can skip over computing the
-stored temperature-dependent intermediate properties.
-This is why we use the term 'manager' rather than 'calculator' 
+A transport manager may do things not apparent to the user in order to
+improve the speed of transport property evaluation. For example, it
+may cache intermediate results that depend only on temperature, so
+that if it happens to be called again at the same temperature (a
+common occurrence) it can skip over computing the stored
+temperature-dependent intermediate properties.  This is why we use the
+term 'manager' rather than 'calculator.'
 
-In the Cantera kernel, each different transport model is implemented by a different class derived from the genericse class Transport. A highly simplified class structure is used in the Python interface -- there is only one class 
-"""
+In the Cantera kernel, each different transport model is implemented
+by a different class derived from the base class Transport. A
+highly simplified class structure is used in the Python interface --
+there is only one class. """
 
 import _cantera
 from Numeric import asarray
@@ -22,19 +24,23 @@ import exceptions
 
 class Transport:
 
-    """Transport property manager.
-    A transport property manager is responsible for computing transport
-    properties.
+    """Transport properties.
+
+    This class provides the Python interface to the family of
+    transport manager classes in the Cantera C++ kernel. A transport
+    manager has one job: to compute transport properties of a phase of
+    matter assigned to it. The phase is represented by an object
+    belonging to a class derived from ThermoPhase.
 
     In the C++ kernel, a transport manager implements a single
     transport model, and is an instance of a subclass of the base
     class 'Transport'.  The structure in Python is a little
     different. A single class 'Transport' represents any kernel-level
     transport manager. In addition, multiple kernel-kevel transport
-    managers may be associated with one Python transport manager,
-    allowing the model used to compute transport properties to be
-    switched at any time.
-    """
+    managers may be installed in one Python transport manager,
+    although only one is active at any one time. This feature allows
+    switching between transport models."""
+    
     def __init__(self, xml_phase=None,
                  phase=None, model = "", loglevel=0):
         """Create a transport property manager.
@@ -42,22 +48,29 @@ class Transport:
         xml_phase --- XML phase element
         phase     --- ThermoPhase instance representing the phase that the
                       transport properties are for
-        model     --- string specifying transport model. If omitted,
-                      model will be taken from the input file.
-        loglevel  --- controls amount of diagnostic output
+        model     --- string specifying transport model. If omitted or
+                      set to 'Default', the model will be read from the
+                      input file.
+        loglevel  --- controls the amount of diagnostic output
         """
-        if model == "" or model == "Default":
+
+        # if the transport model is not specified, look for attribute
+        # 'model' of the XML 'transport' element
+        if model == "" or model == "Default" or model == "default":
             try:
                 self.model = xml_phase.child('transport')['model']
             except:
                 self.model = ""
         else:
             self.model = model
+            
         self.__tr_id = 0
         self.__tr_id = _cantera.Transport(self.model,
                                              phase._phase_id, loglevel)
         self.trnsp = phase.nSpecies()
         self._phase_id = phase._phase_id
+        
+        # dictionary holding all installed transport managers
         self._models = {}
         self._models[self.model] = self.__tr_id
 
@@ -71,7 +84,11 @@ class Transport:
                     pass
 
     def addTransportModel(self, model, loglevel=1):
-        """Add a new transport model to this transport manager."""
+        """Add a new transport model.  Note that if 'model' is the
+        name of an already-installed transport model, the new
+        transport manager will take the place of the old one, which
+        will no longer be accessible. This method does not change the
+        active model."""
         new_id = _cantera.Transport(model,
                                     self._phase_id, loglevel)
         self._models[model] = new_id
@@ -81,11 +98,13 @@ class Transport:
         """Switch to a different transport model."""
         if self._models.has_key(model):
             self.__tr_id = self._models[model]
+            self.model = model
         else:
             raise CanteraError("Transport model "+model+" not defined. Use "
                                +"method addTransportModel first.")
             
     def desc(self):
+        """A short description of the active model."""
         if self.model == 'Multi':
             return 'Multicomponent'
         elif self.model == 'Mix':
@@ -94,12 +113,15 @@ class Transport:
             return self.model
             
     def transport_id(self):
+        """For internal use."""
         return self.__tr_id
 
     def transport_hndl(self):
+        """For internal use."""        
         return self.__tr_id
     
     def viscosity(self):
+        "Viscosity [Pa-s]."""
         return _cantera.tran_viscosity(self.__tr_id)
 
     def thermalConductivity(self):
@@ -124,7 +146,7 @@ class Transport:
 
     def multiDiffCoeffs(self):
         """Two-dimensional array of species multicomponent diffusion
-        coefficients."""
+        coefficients. Not implemented in all transport managers."""
         return _cantera.tran_multiDiffCoeffs(self.__tr_id,
                                            self.trnsp)
 
@@ -133,4 +155,9 @@ class Transport:
         return _cantera.tran_setParameters(self.__tr_id,
                                            type, k, asarray(params))
     
-    
+
+    def molarFluxes(self, state1, state2, delta):
+        return _cantera.tran_getMolarFluxes(self.__tr_id, self.trnsp, 
+                                            asarray(state1), asarray(state2),
+                                            delta)
+