Force Distribution Output

Force Distribution Output#

Force Distribution Output allows you to compute and output force and moment distributions along a custom direction. This is useful for analyzing spanwise loading on wings, chordwise force distributions, or any other directional force analysis that doesn’t align with the standard coordinate axes.

Available Options#

Option

Description

Applicable

Name

Unique identifier for the force distribution output

always

Distribution direction

3D unit vector specifying the direction along which forces and moments are distributed

always

Distribution type

Type of distribution calculation: incremental or cumulative

always

Number of segments

Number of bins along the distribution direction used for sampling

always

Assigned surfaces

Surfaces to include in force integration; if not set, all wall surfaces are used

always

Detailed Descriptions#

Name#

Unique identifier for the force distribution output.

  • Required: Yes

  • Example: "spanwise", "chordwise"

Note: Output names must be unique among all force distribution outputs in the same simulation.

Distribution direction#

The 3D unit vector that specifies the direction along which forces and moments are distributed. The vector is automatically normalized by Flow360.

  • Required: Yes

  • Format: 3-element array [x, y, z] representing a 3D direction vector

  • Example: [0, 1, 0] for spanwise (y-direction), [1, 0, 0] for chordwise (x-direction), [0.1, 0.9, 0] for a custom oblique direction

Note: The vector is automatically normalized, so [0.1, 0.9, 0] and [0.1, 0.9, 0.0] will result in the same normalized direction vector.

Distribution type#

Specifies whether forces and moments are output as incremental (per segment) or cumulative (integrated up to that point). The sampling locations to calculate the force distribution are uniformly distributed along the specified direction in general, but for boundaries which have zero projection on the YZ plane, e.g. a flat floor, the sampling locations are coarser.

  • Required: No

  • Default: "incremental"

  • Options:

    • "incremental" - Outputs force and moment contributions for each segment along the distribution direction

    • "cumulative" - Outputs the cumulative (integrated) force and moment values along the distribution direction

Number of segments#

The number of bins (segments) used to sample the force distribution along the specified direction. Higher values provide finer resolution in the distribution plot.

  • Required: No

  • Default: 300

  • Example: 500 for higher resolution, 100 for a coarser overview

Note: Increasing the number of segments increases output file size and post-processing time.

Assigned surfaces#

The list of surfaces to include in the force integration. If left empty, Flow360 automatically includes all wall surfaces in the simulation.

  • Required: No

  • Default: All wall surfaces (when not specified)

  • How to set: Click + to add surfaces manually, or use the Select from 3D scene button to pick surfaces interactively in the viewer.

  • Example use case: In automotive simulations, exclude the road/floor surface to compute force distributions only over the vehicle body.

Note: Only surfaces assigned a wall boundary condition can be selected.

Use Cases#

Force Distribution Output is useful for:

  • Analyzing spanwise loading distributions on wings or propellers

  • Computing chordwise force distributions

  • Custom directional force analysis (e.g., forces along a sweep direction)

  • Identifying critical loading regions along specific geometric directions

  • Comparing force distributions between different components or configurations

Output Data#

The output provides axis-aligned components of force and moment coefficients along the specified distribution direction. Data is saved in CSV format (pattern: <output_name>_forceDistribution.csv) and can be accessed through the download from the Assets button. It is also possible to visualise the output from the Analysis -> Monitor -> <output_name> tab in webUI.

The output includes force and moment coefficients (CL, CD, CFx, CFy, CFz, CMx, CMy, CMz) distributed along the specified direction.

🐍 Python Example Usage

Basic Force Distribution Output Example

import flow360 as fl

# Create a spanwise force distribution (along y-axis)
spanwise_distribution = fl.ForceDistributionOutput(
    name="spanwise",
    distribution_direction=[0, 1, 0],  # Y-direction
    distribution_type="cumulative"
)

Force Distribution Output with custom segments and surface selection

import flow360 as fl

# Higher-resolution chordwise distribution on selected surfaces only
chordwise_distribution = fl.ForceDistributionOutput(
    name="chordwise",
    distribution_direction=[1, 0, 0],  # X-direction
    distribution_type="incremental",
    number_of_segments=500,                    # finer resolution
    surfaces=[volume_mesh["wing_upper"],        # restrict to wing surfaces only
               volume_mesh["wing_lower"]],
)
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