AQWA Analysis Skill

Hub for ANSYS AQWA hydrodynamic analysis — RAO computation, added mass/damping extraction, coefficient management.

When to Use

• RAO (Response Amplitude Operator) computation
• Hydrodynamic coefficient extraction (added mass, damping)
• Viscous damping determination
• Diffraction/radiation analysis (AQWA-LINE)
• Time domain motions (AQWA-DRIFT)
• Stability analysis (AQWA-LIBRIUM)
• Cable dynamics (AQWA-NAUT), coupled analysis (AQWA-WAVE)

Prerequisites

• Python environment with digitalmodel package
• AQWA output files (LIS, DAT, or MES format)
• For running AQWA: ANSYS AQWA license

Industry Standards

• DNV-RP-C205 (Environmental Conditions)
• API RP 2SK (Stationkeeping)
• ISO 19901-7 (Mooring Systems)
• IEC 61400-3 (Wind Turbines)

Python API

RAO Extraction

from digitalmodel.aqwa.aqwa_raos import AqwaRAOs

raos = AqwaRAOs()
raos.load("aqwa_results/vessel.LIS")

surge_rao = raos.get_rao(motion="surge", wave_direction=180.0)
rao_df = raos.to_dataframe()

raos.plot_rao(
    motions=["heave", "pitch", "roll"],
    directions=[0, 90, 180],
    output_file="results/rao_comparison.html"
)
raos.export_orcaflex("vessel_raos.yml")

Analysis Router

from digitalmodel.aqwa.aqwa_analysis import AqwaAnalysis

aqwa = AqwaAnalysis()
cfg = {
    "aqwa": {
        "input_file": "aqwa_results/vessel.LIS",
        "extract": ["raos", "added_mass", "damping", "drift_forces"],
        "output_directory": "results/"
    }
}
results = aqwa.run(cfg)

Coefficient Extraction

from digitalmodel.aqwa.aqwa_reader import AqwaReader

reader = AqwaReader()
data = reader.read("aqwa_results/vessel.LIS")

added_mass = data.get_added_mass(0.1)  # 6x6 numpy array at ω=0.1 rad/s
damping = data.get_damping(0.1)

Pre-Processing

from digitalmodel.aqwa.aqwa_preprocess import AqwaPreProcess

preprocess = AqwaPreProcess()
preprocess.generate_input(
    vessel_geometry="geometry/hull.stl",
    water_depth=1000.0,
    wave_frequencies=[0.05, 0.1, 0.15, 0.2, 0.3, 0.5, 0.8, 1.0],
    wave_directions=[0, 45, 90, 135, 180],
    output_file="aqwa_input/vessel.dat"
)

Key Classes

Related Skills

• aqwa/input — Analysis configs, file formats, DAT conventions, mesh quality
• aqwa/output — Output formats, validation, benchmarks
• aqwa/reference — Solver stages, OPTIONS keywords, FIDP/FISK cards
• aqwa/batch-execution — Batch run orchestration
• diffraction-analysis — Master skill for all diffraction workflows
• bemrosetta — AQWA to OrcaFlex conversion
• orcawave/analysis — Benchmark validation

References

• ANSYS AQWA User Manual
• DNV-RP-C205: Environmental Conditions and Environmental Loads
• Newman, J.N.: Marine Hydrodynamics