Floating Offshore Structure Simulation

Overview

Objective and scope

This study audited and reran a SPAR-type floating-structure workflow from copied solver decks. The public case focuses on what was checked: equilibrium, diffraction/RAO behavior, mooring-database warnings, and a fresh time response - alongside the material warnings that still bound interpretation.

Engineering question

A simulation can complete while still containing assumptions or warnings that change how far its result can be trusted. The work therefore treats warning review and reproducibility as engineering tasks, not post-processing details.

Objectives

• Record a reproducible AQWA evidence chain for equilibrium and diffraction/RAO checks.
• Investigate the mooring Z-range warning before relying on a fresh time response.
• Separate learning-model acceptance from client-design or certification claims.

Method

How the work was approached

• Audit retained solver decks and outputs without modifying the original reference archive.
• Run fresh equilibrium and diffraction analyses from copied/staged decks, then compare traceable values with retained targets.
• Extend the copied mooring database range, confirm equilibrium did not shift, and run a fresh irregular-wave response.

Tools

Assumptions and boundaries

• The model is a learning and reproducibility case, not a project-specific floating-system design basis.
• Fresh diffraction retains a 6.3109% vertical hydrostatic imbalance and a negative-buoyancy warning that remain material caveats.
• The fresh time response is one 600 s realization, not an ensemble for final extreme-response statistics.

Evidence

What the public case is based on

• Final Engineering Learning Report, sections 4-11.
• AQWA Reproducibility Report and fresh-rerun verification JSON files.
• Final report data summary generated from retained outputs only.

Validation

• Fresh equilibrium matched retained final position and recorded residual behavior.
• Fresh diffraction/RAO matched retained hydrostatic, wave-grid, and RAO targets while preserving material warning status.
• The copied-deck mooring range change removed 156 Z-range warnings without changing the final equilibrium Z value.

Results

Selected, bounded observations

6,001

fresh time-response records600 s at 0.1 s output interval

156 -> 0

Z-range warningsafter copied-deck mooring range adjustment

6.3109%

hydrostatic imbalancematerial caveat retained in diffraction

Reported results

• The fresh irregular-wave run retained 6,001 records over 600 s at a 0.1 s output interval.
• The retained RAO summary contains 175 displacement points; peak values are shown as a learning-model sensitivity result, not a design acceptance criterion.
• The Z-range warning count changed from 156 to 0 after the copied-deck range adjustment; mean line tension remained about 92.98 kN in the stated model context.

Key takeaways

• A solver exit code is not enough: hydrostatic, buoyancy, and mooring-database warnings must remain visible beside the response plots.
• The range correction made a fresh time-response run possible, but it did not remove the remaining model-basis caveats.

Limitations

• Student engineering study for learning and portfolio purposes; it is not a certified design deliverable.
• The study does not provide code compliance, final fatigue or buckling, a complete metocean design basis, or multi-seed 100-year extreme statistics.

What I learned

• Treat the warning register as a first-class engineering output.
• Use copied decks and hashes when a reproducibility exercise must preserve original reference material.

Evidence trail