Time-averaging Streamline Output

Time-averaging Streamline Output#

Time-averaging Streamline Output in Flow360 allows you to visualize time-averaged streamlines during unsteady simulations. Streamtraces are computed upwind and downwind, and may originate from a single point, from a line, or from points evenly distributed across a parallelogram.

Note: Time-averaging outputs are only available when using unsteady time stepping methods.

Available Options#

Option

Description

Output fields

Flow variables to include along streamlines

Start step

Physical time step to start calculating averaging

Assigned points

Points indicating the locations of streamlines

Detailed Descriptions#

Output fields#

The flow variables that will be included along the time-averaged streamlines.

  • Default: None

  • Example: pressure, velocity, Mach

Note: Vector-valued fields will be colored by their magnitude. See Available Output Fields for a complete list of supported variables.

Start step#

The physical time step at which time-averaging begins.

  • Required: Yes

  • Default: None

  • Example: 100 (begin averaging from the 100th physical time step)

Notes:

  • Use positive integers to start averaging from a specific time step.

  • Set this to a time step after initial transients have settled for more meaningful statistics.

  • Important for child cases - this parameter refers to the global time step, which gets transferred from the parent case. See Global Time Stepping in Child Cases for more details.

Assigned points#

Points that define the placement of streamlines. Streamtraces are computed upwind and downwind, and may originate from a single point, from a line, or from points evenly distributed across a parallelogram.

  • Point Definition: The creation of points is described in detail here

Notes:

  • You can specify individual points or arrays of points to seed streamlines at multiple locations.

  • Points can be defined in the GUI or via the Python API.

🐍 Python Example Usage

 
# Example of setting up time-averaged streamline output in Python
time_avg_streamline_output = fl.TimeAverageStreamlineOutput(
    entities=[
        fl.Point(
            name="Point_1",
            location=(0.0, 1.5, 0.0) * fl.u.m,
        ),
        fl.Point(
            name="Point_2",
            location=(0.0, -1.5, 0.0) * fl.u.m,
        ),
        fl.PointArray(
            name="Line_streamline",
            start=(1.0, 0.0, 0.0) * fl.u.m,
            end=(1.0, 0.0, -10.0) * fl.u.m,
            number_of_points=11,
        ),
        fl.PointArray2D(
            name="Parallelogram_streamline",
            origin=(1.0, 0.0, 0.0) * fl.u.m,
            u_axis_vector=(0, 2.0, 2.0) * fl.u.m,
            v_axis_vector=(0, 1.0, 0) * fl.u.m,
            u_number_of_points=11,
            v_number_of_points=20
        )
    ],
    output_fields=[fl.solution.pressure, fl.solution.velocity],
    start_step=400,
)
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