Settings objects#

Settings objects provide a natural way to access and modify Fluent settings and issue commands with a hierarchy of objects.

Top-level settings objects#

The top-level settings object is available as the root property of session.solver.

>>> import ansys.fluent.core as pyfluent
>>> solver = pyfluent.launch_fluent(mode="solver")
>>> root = solver

The root object contains attributes such as file, setup, solution, and results. These objects are also instances of settings objects and roughly mirror the outline view in Fluent.

Types of settings objects#

A settings object can be one of the primitive types, like Integer, Real, String, and Boolean. It can also be a container object, of which there are three types: Group, NamedObject, and ListObject.

  • The Group type is a static container with predefined child objects that can be accessed via attributes. For example, refers to the energy child of the models child of the setup object. The names of the child objects of a group can be accessed with the child_names attribute of a Group object.

  • The NamedObject type is a container holding dynamically created named objects of its specified child type (accessible via a child_object_type attribute), similar to a dictionary. A specified named object can be accessed using the index operator. For example, root.setup.boundary_conditions.velocity_inlet['inlet2'] refers to the velocity_object object with the name inlet2. The current list of named object children can be accessed with the get_object_names() method of the container class.

  • The ListObject type is a container holding dynamically created unnamed objects of its specified child type (accessible via a child_object_type attribute) in a list. Children of a ListObject object can be accessed using the index operator. For example, root.setup.cell_zone_conditions.fluid['fluid-1'].source_terms['mass'][2] refers to the third (starting from index 0) mass source entry for the fluid zone named fluid-1. The current number of child objects can be accessed with the get_size() method.

Object state#

You can access the state of any object by “calling” it. For container objects, this returns the state of the children as a dictionary for Group and NamedObject types or as a list for ListObject types:

>>> root.setup.models.viscous.model()
>>> from pprint import pprint
>>> pprint (
{'enabled': True,
 'inlet_diffusion': True,
 'kinetic_energy': False,
 'pressure_work': False,
 'viscous_dissipation': False}
>>> root.setup.boundary_conditions.velocity_inlet['inlet1'].vmag.constant()

To modify the state of any object, you can assign the corresponding attribute in its parent object. This assignment can be done at any level. For Group and NamedObject types, the state value is a dictionary. For the ListObject type, the state value is a list.

>>> root.setup.models.viscous.model = 'laminar'
>>> = { 'enabled' : False }
>>> root.setup.boundary_conditions.velocity['inlet1'].vmag.constant = 14

You can also access the state of an object with the get_state method and modify it with the set_state method.

You can print the current state in a simple text format with the print_state method. For example, assume you entered:

>>> root.setup.models.print_state()

The following output is returned:

viscous :
  k_epsilon_model : standard
  near_wall_treatment : standard-wall-fn?
  model : k-epsilon-standard
  options :
    viscous_heating : False
    curvature_correction : False
    production_kato_launder : False
    production_limiter : False
energy :
  enabled : True
  pressure_work : False
  viscous_dissipation : False
  inlet_diffusion : True
  kinetic_energy : False
multiphase :
  number_of_phases : 0
  models : none


Commands are methods of settings objects that you use to modify the state of the application. For example, the hybrid_initialize() method of solution.initialization initializes the solution using the hybrid initialization method. The command_names attribute of a settings object provides the names of its commands.

If keyword arguments are needed, you can use commands to pass them. To access a list of valid arguments, use the arguments attribute. If you do not specify an argument, its default value is used. Arguments are also settings objects and can be either the primitive type or the container type.

Additional metadata#

Settings objects have some additional metadata that you can use the get_attr and get_attrs methods to access.

This example accesses the list of allowed values at a particular state for the viscous model:

>>> root.setup.models.viscous.model.get_attr('allowed-values')
['inviscid', 'laminar', 'k-epsilon-standard', 'k-omega-standard', 'mixing-length', 'spalart-allmaras', 'k-kl-w', 'transition-sst', 'reynolds-stress', 'scale-adaptive-simulation', 'detached-eddy-simulation', 'large-eddy-simulation']
>>> root.setup.models.viscous.model.get_attrs(['allowed-values'])
{'allowed-values': ['inviscid', 'laminar', 'k-epsilon', 'k-omega', 'mixing-length', 'spalart-allmaras', 'k-kl-w', 'transition-sst', 'reynolds-stress', 'scale-adaptive-simulation', 'detached-eddy-simulation', 'large-eddy-simulation']}

This example accesses the list of zone surfaces:

>>> root.solution.report_definitions.flux["mass_flow_rate"] = {}
>>> root.solution.report_definitions.flux[
['symmetry-xyplane', 'hot-inlet', 'cold-inlet', 'outlet', 'wall-inlet', 'wall-elbow', 'interior--elbow-fluid']
>>> root.solution.report_definitions.flux["mass_flow_rate"] = {}
>>> root.solution.report_definitions.flux[
{'allowed-values': ['symmetry-xyplane', 'hot-inlet', 'cold-inlet', 'outlet', 'wall-inlet', 'wall-elbow', 'interior--elbow-fluid']}

Attributes are dynamic. Values can change based on the app state.

Active objects and commands#

Objects and commands can be active or inactive based on the app state. The is_active() method returns True if an object or command is active at a particular time.

The get_active_child_names method returns the list of active children:

>>> root.setup.models.get_active_child_names()
['energy', 'multiphase', 'viscous']

The get_active_command_names method returns the list of active commands:

>>> root.solution.run_calculation.get_active_command_names()

Root object#

The root object is the top-level settings object. It contains all other settings objects in a hierarchical structure. For more information, see root.