Surface Probe Outputs

Surface Probe Outputs#

Surface probe outputs allow you to monitor flow field variables at points projected onto specific surfaces, providing targeted surface data at precise locations during your simulation.

Available Options#

Option

Description

Output fields

Flow variables to monitor at projected locations

Assigned probes

Points or point arrays that will be projected onto surfaces

Assigned target boundaries

Surfaces onto which the probes will be projected

Detailed Descriptions#

Output fields#

The flow variables that will be monitored at the specified probe locations projected onto surfaces.

  • Default: None (user must select at least one field)

  • Example: Cp, Cf, yPlus

Notes:

  • Select only the fields you need for your analysis.

  • Surface-specific variables are available.

Assigned probes#

The specific points or arrays of points that will be projected onto surfaces for monitoring. The projection is executed at the start of the simulation. If the surface that the point was projected to is moving (mesh motion), the point moves with it (it remains stationary in the reference frame of the target surface).

  • Default: None (user must define at least one probe)

  • Example: A point at (0, 1.5, 0), or a line of points between two locations

Note: Points are projected to the nearest point on the target surfaces.

  • Adding Probes:

    • Click the “+” button or “Select from 3D scene or list” button in the Probes section

    • Choose “New point” to add a single probe point

    • Choose “New point array” to create a line of evenly spaced points

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

Assigned target boundaries#

The surfaces onto which the probe points will be projected for monitoring.

  • Default: None (user must select at least one surface)

  • Example: Wing, Fuselage

Note: Points are projected to the nearest location on these surfaces. If a point could be projected to multiple surfaces, it will be projected to the closest one.

Available Output Fields#

Surface probe outputs share the same output fields that are available for Surface Outputs, including both universal variables and surface-specific variables.

💡 Tips

  • Place probe points close to surfaces of interest for more accurate projections.

  • Use point arrays to track values across a span or chord of aerodynamic surfaces.

  • Choose descriptive names for both probes and outputs to easily identify them in post-processing.

  • For boundary layers, place points slightly away from the surface and project them to monitor properties at specific locations.

Efficient Probe Placement:

  • When monitoring airfoil sections, place point arrays along chord lines at different span positions.

  • For symmetric geometries, consider placing probes on only one side to reduce output data volume.

  • Start with fewer points and add more as needed to refine your analysis.

  • Verify probe projections in post-processing visualization before running long simulations.

❓ Frequently Asked Questions

  • What’s the difference between Probe Output and Surface Probe Output?

    Probe output monitors flow variables at exact 3D coordinates within the volume, while Surface Probe Output projects the specified points onto the nearest surface and monitors variables at those projected locations.

  • What happens if my probe point is far from any surface?

    The point will still be projected to the nearest surface location, but the values may not be representative of what you’re trying to measure. It’s best to place probe points close to the surfaces of interest.

  • Can I monitor multiple variables at the same projected point?

    Yes, you can select multiple output fields for any surface probe point.

  • How do I ensure my probe point is projected to the correct surface?

    If you have multiple target surfaces, the probe will be projected to the closest surface. If you want to ensure projection to a specific surface, either place the probe very close to that surface or only include that specific surface in the target boundaries list.

🐍 Python Example Usage

 
# Define a surface probe output
surface_probe_output = fl.SurfaceProbeOutput(
    name="wing_surface_monitors",
    entities=[  # The entities list corresponds to the 'Assigned probes' section in the GUI
        fl.Point(
            name="Leading_Edge",
            location=(0.0, 1.5, 0.0) * fl.u.m,
        ),
        fl.Point(
            name="Trailing_Edge",
            location=(1.0, 1.5, 0.0) * fl.u.m,
        ),
        fl.PointArray(
            name="Wing_Section",
            start=(0.2, 0.0, 0.0) * fl.u.m,
            end=(0.8, 0.0, 0.0) * fl.u.m,
            number_of_points=11,
        ),
    ],
    target_surfaces=[  # The target_surfaces list corresponds to the 'Assigned target boundaries' section in the GUI
        geometry["wing"],
    ],
    output_fields=["Cp", "Cf", "yPlus"],
)
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