OrcaFlex RAO Import Skill

Import, validate, and process RAO data from external sources for OrcaFlex vessel type creation.

Version Metadata

version: 1.0.0
python_min_version: '3.10'
dependencies:
  orcaflex-modeling: '>=2.0.0,<3.0.0'
  hydrodynamics: '>=1.0.0,<2.0.0'
orcaflex_version: '>=11.0'
compatibility:
  tested_python:
  - '3.10'
  - '3.11'
  - '3.12'
  - '3.13'
  os:
  - Windows
  - Linux
  - macOS

Changelog

[1.0.0] - 2026-01-17

Added:

Initial release with multi-format RAO import
AQWA .lis file parsing
OrcaFlex YAML RAO extraction
Validation and interpolation
OrcaFlex vessel type export

When to Use

Import RAOs from ANSYS AQWA analysis
Extract RAOs from existing OrcaFlex models
Import RAOs from experimental data (CSV/Excel)
Validate RAO data quality
Interpolate RAOs to new frequency/heading grids
Create OrcaFlex vessel types with imported RAOs

Supported Formats

| Source | Format | Extension | Support Level | |--------|--------|-----------|---------------| | ANSYS AQWA | LIS output | .lis | Full | | OrcaFlex | YAML | .yml | Full | | Excel | Tabular | .xlsx | Full | | CSV | Tabular | .csv | Full | | WAMIT | Output | .out | Planned | | HydroD | Database | .h5 | Planned |

RAO Data Structure

6-DOF Motion RAOs

| DOF | Description | Units (Amplitude) | Units (Phase) | |-----|-------------|-------------------|---------------| | Surge | Translation X | m/m | deg | | Sway | Translation Y | m/m | deg | | Heave | Translation Z | m/m | deg | | Roll | Rotation X | deg/m | deg | | Pitch | Rotation Y | deg/m | deg | | Yaw | Rotation Z | deg/m | deg |

Configuration

Basic Import Configuration

# configs/rao_import.yml

rao_import:
  source:
    type: "aqwa"
    file: "data/hydrodynamics/vessel_aqwa.lis"

  # Target frequency grid
  frequencies:
    min: 0.02    # rad/s
    max: 2.0
    count: 50

  # Target heading grid
  headings:
    values: [0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, 180]
    symmetry: "port_starboard"  # Mirror for 180-360

  # Validation settings
  validation:
    enabled: true
    amplitude_limits:
      surge: 10.0    # m/m
      sway: 10.0
      heave: 5.0
      roll: 50.0     # deg/m
      pitch: 20.0
      yaw: 30.0
    phase_continuity_check: true
    frequency_range_check: true

  # Output
  output:
    format: "orcaflex_yml"
    file: "output/vessel_raos.yml"

Multi-Source Import

# configs/rao_multi_import.yml

rao_import:
  sources:
    - name: "full_load"
      type: "aqwa"
      file: "data/vessel_full_load.lis"
      loading_condition: "Full Load"

    - name: "ballast"
      type: "aqwa"
      file: "data/vessel_ballast.lis"
      loading_condition: "Ballast"

  interpolation:
    method: "cubic"
    target_frequencies: "common_grid"
    target_headings: [0, 30, 60, 90, 120, 150, 180]

  output:
    combined_file: "output/vessel_raos_combined.yml"
    separate_files: true

Python API

Basic RAO Import

from digitalmodel.modules.marine_analysis.rao_processor import RAOProcessor

# Initialize processor
processor = RAOProcessor()

# Import from AQWA
rao_data = processor.import_from_aqwa(
    file_path="data/vessel.lis",
    vessel_name="FPSO"
)

# Access data
print(f"Frequencies: {rao_data.frequencies}")
print(f"Headings: {rao_data.headings}")
print(f"DOFs: {rao_data.dofs}")

# Get specific RAO
heave_rao = rao_data.get_rao("heave", heading=90)
print(f"Heave RAO at 90 deg: Amplitudes = {heave_rao['amplitude']}")

AQWA File Reading

from digitalmodel.modules.marine_analysis.aqwa_reader import AQWAReader

# Initialize reader
reader = AQWAReader()

# Read AQWA .lis file
aqwa_data = reader.read_lis_file("data/vessel_aqwa.lis")

# Extract motion RAOs
raos = reader.extract_motion_raos(aqwa_data)

# Structure:
# raos = {
#     "frequencies": [...],
#     "headings": [...],
#     "surge": {"amplitude": [[...]], "phase": [[...]]},
#     "sway": {...},
#     "heave": {...},
#     "roll": {...},
#     "pitch": {...},
#     "yaw": {...}
# }

OrcaFlex RAO Reading

from digitalmodel.modules.marine_analysis.orcaflex_reader import OrcaFlexRAOReader

# Initialize reader
reader = OrcaFlexRAOReader()

# Read from OrcaFlex model
rao_data = reader.read_from_model("models/vessel_model.yml")

# Or read from vessel type definition
rao_data = reader.read_vessel_type("data/vessel_types/fpso_type.yml")

RAO Validation

from digitalmodel.modules.marine_analysis.rao_validators import RAOValidator

# Initialize validator
validator = RAOValidator()

# Define validation limits
limits = {
    "surge": 10.0,
    "sway": 10.0,
    "heave": 5.0,
    "roll": 50.0,
    "pitch": 20.0,
    "yaw": 30.0
}

# Validate RAO data
validation_result = validator.validate(
    rao_data,
    amplitude_limits=limits,
    check_phase_continuity=True,
    check_frequency_range=True
)

if validation_result.is_valid:
    print("RAO data passed validation")
else:
    for issue in validation_result.issues:
        print(f"Issue: {issue}")

# Get detailed report
report = validator.generate_validation_report(validation_result)

RAO Interpolation

from digitalmodel.modules.marine_analysis.rao_interpolator import RAOInterpolator

# Initialize interpolator
interpolator = RAOInterpolator()

# Define target grid
target_frequencies = np.linspace(0.02, 2.0, 100)
target_headings = np.arange(0, 181, 15)

# Interpolate
interpolated_raos = interpolator.interpolate_2d(
    rao_data,
    target_frequencies=target_frequencies,
    target_headings=target_headings,
    method="cubic"
)

# Quality assessment
quality = interpolator.assess_quality(rao_data, interpolated_raos)
print(f"Interpolation R²: {quality['r_squared']:.4f}")

Export to OrcaFlex Format

from digitalmodel.modules.marine_analysis.rao_processor import RAOProcessor

processor = RAOProcessor()

# Export to OrcaFlex YAML format
processor.export_to_orcaflex(
    rao_data,
    output_file="vessel_type.yml",
    vessel_name="FPSO_RAOs",
    include_metadata=True
)

# The output file can be directly loaded in OrcaFlex
# as a vessel type DisplacementRAOs section

Complete Workflow

from digitalmodel.modules.marine_analysis.rao_processor import RAOProcessor
from digitalmodel.modules.marine_analysis.rao_validators import RAOValidator
from digitalmodel.modules.marine_analysis.rao_interpolator import RAOInterpolator

# 1. Import RAOs
processor = RAOProcessor()
raw_raos = processor.import_from_aqwa("data/vessel.lis")

# 2. Validate
validator = RAOValidator()
validation = validator.validate(raw_raos)

if not validation.is_valid:
    print("Validation issues found:")
    for issue in validation.issues:
        print(f"  - {issue}")
    # Handle issues or continue with warnings

# 3. Interpolate to OrcaFlex-compatible grid
interpolator = RAOInterpolator()
interpolated = interpolator.interpolate_2d(
    raw_raos,
    target_frequencies=np.linspace(0.05, 1.5, 50),
    target_headings=[0, 45, 90, 135, 180]
)

# 4. Apply port/starboard symmetry
symmetric = processor.apply_symmetry(interpolated, "port_starboard")

# 5. Export for OrcaFlex
processor.export_to_orcaflex(
    symmetric,
    output_file="vessel_raos.yml",
    vessel_name="FPSO"
)

print("RAO import complete!")

Output Formats

OrcaFlex YAML Format

VesselTypes:
  - Name: FPSO_RAOs
    DisplacementRAOs:
      RAOOrigin: [150.0, 0.0, 0.0]  # meters from vessel origin
      Directions: [0, 45, 90, 135, 180]  # degrees
      Periods: [5.0, 7.0, 10.0, 12.0, 15.0, 20.0]  # seconds

      # Amplitude and Phase for each DOF
      # Format: [heading][period]
      SurgeAmp:
        - [0.12, 0.25, 0.45, 0.52, 0.48, 0.35]  # 0 deg
        - [0.10, 0.22, 0.40, 0.48, 0.44, 0.32]  # 45 deg
        # ... more headings

      SurgePhase:
        - [0, 10, 25, 45, 60, 80]
        # ...

      # Similar for Sway, Heave, Roll, Pitch, Yaw

DataFrame Export

# Export to DataFrame for analysis
df = processor.to_dataframe(rao_data)

# Multi-level columns: (DOF, Heading)
# Index: Frequency
print(df.head())
#           Surge                    Sway
#           0      45     90        0      45     90
# 0.02      0.95   0.92   0.88     0.02   0.45   0.92
# 0.05      0.92   0.90   0.85     0.05   0.48   0.95

Validation Report

{
  "is_valid": false,
  "issues": [
    {
      "type": "amplitude_exceeded",
      "dof": "roll",
      "heading": 90,
      "frequency": 0.6,
      "value": 55.2,
      "limit": 50.0
    },
    {
      "type": "phase_discontinuity",
      "dof": "heave",
      "heading": 45,
      "location": "frequency 0.45 rad/s"
    }
  ],
  "warnings": [
    "Frequency range may not cover peak responses"
  ],
  "statistics": {
    "frequency_range": [0.02, 1.5],
    "heading_range": [0, 180],
    "max_amplitudes": {
      "surge": 0.95,
      "sway": 1.02,
      "heave": 1.85,
      "roll": 55.2,
      "pitch": 12.3,
      "yaw": 8.5
    }
  }
}

Best Practices

Data Quality

Check source analysis - Verify AQWA/WAMIT converged
Review frequency range - Cover wave spectrum
Check peak responses - Resonance captured
Validate symmetry - Port/starboard consistent

Interpolation

Don't extrapolate - Stay within data range
Preserve peaks - Use adequate resolution
Check quality metrics - R² should be > 0.95
Compare with source - Spot-check values

OrcaFlex Integration

RAO origin - Match vessel coordinate system
Period vs frequency - OrcaFlex uses periods
Phase convention - Check sign convention
Test static equilibrium - Verify RAO application

Error Handling

from digitalmodel.modules.marine_analysis.rao_processor import RAOImportError

try:
    rao_data = processor.import_from_aqwa("data/vessel.lis")
except RAOImportError as e:
    print(f"Import failed: {e}")
    print(f"Suggestions: {e.suggestions}")

except FileNotFoundError:
    print("AQWA file not found")

except ValueError as e:
    print(f"Data format error: {e}")

Common Issues

AQWA Import

| Issue | Cause | Solution | |-------|-------|----------| | Missing DOFs | AQWA output incomplete | Check AQWA run settings | | Wrong units | Unit conversion | Specify units in config | | Truncated data | Large file | Use streaming reader |

Interpolation

| Issue | Cause | Solution | |-------|-------|----------| | Oscillations | Sparse data | Use linear interpolation | | NaN values | Out of range | Extend source data | | Poor fit | Non-smooth data | Review source quality |

Related Skills

orcaflex-modeling - Apply imported RAOs
orcawave-analysis - Generate RAOs from diffraction
aqwa-analysis - AQWA-specific processing
hydrodynamics - Hydrodynamic coefficient management

References

OrcaFlex: Vessel Type RAO Data
ANSYS AQWA: Output File Formats
Source: src/digitalmodel/modules/marine_analysis/rao_processor.py
Source: src/digitalmodel/modules/marine_analysis/aqwa_reader.py
Source: src/digitalmodel/modules/marine_analysis/orcaflex_reader.py
User Story: .ai/specs/modules/user-story-rao-data-import-processing-2025.md

orcaflex-rao-import

OrcaFlex RAO Import Skill

Version Metadata

Changelog

[1.0.0] - 2026-01-17

When to Use

Supported Formats

RAO Data Structure

6-DOF Motion RAOs

Configuration

Basic Import Configuration

Multi-Source Import

Python API

Basic RAO Import

AQWA File Reading

OrcaFlex RAO Reading

RAO Validation

RAO Interpolation

Export to OrcaFlex Format

Complete Workflow

Output Formats

OrcaFlex YAML Format

DataFrame Export

Validation Report

Best Practices

Data Quality

Interpolation

OrcaFlex Integration

Error Handling

Common Issues

AQWA Import

Interpolation

Related Skills

References