Observing events

Each session object has an events child of type EventsManager. You can call the events.register_callback() method in order to receive notifications of various events occurring in Fluent. (The EventsManager object calls each callback whenever a Fluent event occurs, passing the relevant session object and event information as arguments to the callback). The EventsManager object is useful for solution monitoring and dynamic update of graphics.

Supported events are enumerated by the PyFluent SolverEvent and MeshingEvent classes.

The following code triggers a callback at the end of every iteration.

>>> from ansys.fluent.core import SolverEvent, IterationEndedEventInfo
>>>
>>> def on_iteration_ended(session, event_info: IterationEndedEventInfo):
>>>     print("Iteration ended. Index = ", event_info.index)
>>>
>>> callback_id = solver.events.register_callback(SolverEvent.ITERATION_ENDED, on_iteration_ended)

The general signature of the callback function is cb(session, event_info, <additional arguments>), where session is the session instance and event_info instance holds information about the event. The event information classes for each event are documented in the API reference of the events_streaming module. See the callback function on_case_loaded_with_args() in the below examples for an example of how to pass additional arguments to the callback function.

Examples

>>> from ansys.fluent.core import MeshingEvent, SolverEvent
>>> from ansys.fluent.core import CaseLoadedEventInfo, DataLoadedEventInfo, SolutionInitializedEventInfo, IterationEndedEventInfo
>>> from ansys.fluent.core.utils.event_loop import execute_in_event_loop_threadsafe
>>> from ansys.fluent.visualization.matplotlib import matplot_windows_manager
>>> from ansys.fluent.visualization.pyvista import pyvista_windows_manager
>>> from ansys.fluent.visualization import Graphics
>>>
>>> graphics = Graphics(session=solver)
>>>
>>> contour1 = graphics.Contours["contour-1"]
>>> contour1.field = "temperature"
>>> contour1.surfaces_list = ["symmetry"]
>>>
>>> contour2 = graphics.Contours["contour-2"]
>>> contour2.field = "velocity-magnitude"
>>> contour2.surfaces_list = ["symmetry"]
>>>
>>> @execute_in_event_loop_threadsafe
>>> def auto_refersh_call_back_iteration(session, event_info: IterationEndedEventInfo):
>>>   if event_info.index % 5 == 0:
>>>       pyvista_windows_manager.refresh_windows(session.id, ["contour-1", "contour-2"])
>>>       matplot_windows_manager.refresh_windows("", ["residual"])
>>>
>>> callback_itr_id = solver.events.register_callback(SolverEvent.ITERATION_ENDED, auto_refersh_call_back_iteration)
>>>
>>> @execute_in_event_loop_threadsafe
>>> def initialize_call_back(session, event_info: SolutionInitializedEventInfo | DataLoadedEventInfo):
>>>     pyvista_windows_manager.refresh_windows(session.id, ["contour-1", "contour-2"])
>>>     matplot_windows_manager.refresh_windows("", ["residual"])
>>>
>>> callback_init_id = solver.events.register_callback(SolverEvent.SOLUTION_INITIALIZED, initialize_call_back)
>>>
>>> callback_data_read_id = solver.events.register_callback(SolverEvent.DATA_LOADED, initialize_call_back)
>>>
>>> def on_case_loaded(session, event_info: CaseLoadedEventInfo):
>>>     print("Case loaded. Index = ", event_info.index)
>>>
>>> def on_case_loaded_with_args(session, event_info: CaseLoadedEventInfo, x, y):
>>>     print(f"Case loaded with {x}, {y}. Index = ", event_info.index)
>>>
>>> callback = meshing.events.register_callback(MeshingEvent.CASE_LOADED, on_case_loaded)
>>>
>>> callback_case = solver.events.register_callback(SolverEvent.CASE_LOADED, on_case_loaded)
>>>
>>> callback_case_with_args = solver.events.register_callback(SolverEvent.CASE_LOADED, on_case_loaded_with_args, 12, y=42)
>>>