OrcaFlex Jumper Analysis Skill

Description

Rigid and flexible jumper modelling in OrcaFlex — covers installation analysis (crane lift, lowering, landing), in-place analysis (VIV, fatigue, extreme response), and parametric studies across environmental headings and sea states.

When to Use

• Jumper installation analysis (SZ/DZ, AHC on/off)
• Rigid jumper stress analysis and VIV screening
• Flexible jumper fatigue assessment
• Multi-section pipe modelling with buoyancy modules
• Three-point lift rigging design
• Parametric heading/sea-state studies

Key Concepts

Multi-Section Pipe

• Jumpers typically have 15-25 OrcaFlex line sections with alternating line types
• Line types: bare coated pipe, buoyancy modules, strake sections, insulation
• Each section has distinct OD, wall thickness, mass, and bending stiffness
• Section lengths vary: short connector sections (1-2m) to long pipe runs (50-100m)

M-Shape Buoyancy Layout

• Mid-span buoyancy modules create characteristic M-shape in water column
• Module dimensions: typically 10m blocks, density ~0.694 te/m3
• Buoyancy placement defined by arc-length ranges along jumper
• Net buoyancy per module determines equilibrium shape

Rigid End Connectors

• Modelled as separate short OrcaFlex lines with very high bending stiffness
• Typical: OCS 200-V connectors, OD ~1.8m, length ~0.5-1.0m
• EndBxBendingStiffness: 1.0e+307 (effectively rigid)
• Connected to main jumper via end connections

Installation Rigging Chain

The full lift system from vessel to jumper, modelled as linked OrcaFlex objects:

1. Vessel — Installation vessel with RAOs
2. Crane Pedestal — 6DBuoy at vessel crane location
3. Crane Boom — Constraint object (boom geometry)
4. Crane Wire — Winch object (main hoist)
5. Sling — Line from winch to masterlink
6. Masterlink — 3DBuoy (central connection point)
7. Slings — Lines from masterlink to spreader bar ends
8. Spreader Bar — 6DBuoy (~120ft / 36.6m)
9. Lift Slings + Turnbuckles — Lines from spreader bar to clamp points
10. Clamps — Attached to jumper at pickup arc lengths

Three-Point Lift

• Spreader bar with asymmetric pickup at 3 arc-length positions
• Pickup points determined by jumper COG and weight distribution
• Typical: 5 clamps (10-inch jumper clamps, ~0.26 te each) at sling points
• COG calculation considers all KIT weights (~46 te total for 4 KITs)

AHC System (Active Heave Compensation)

• Modelled via Winch + ExternalFunction (DLL)
• Two analysis variants: AHC-on (DZ) and AHC-off (SZ)
• ExternalFunction64.dll provides real-time heave compensation
• AHC reduces dynamic tension variation during lowering

Dual-Zone Analysis

Coatings & Insulation

Two-Step Statics

• Step 1: User-specified starting positions (rigging geometry)
• Step 2: Full statics solve (catenary + equilibrium)
• Critical for installation models where initial geometry is non-trivial

Parametric Studies

• Environmental headings: 0, 30, 60, 90, 120, 150, 165, 180 degrees
• Sea states: Hs = 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.5m
• Seeds: 20+ random seeds per (heading, Hs) combination
• Total runs per jumper: 200-1000+ simulations

Model Library

Available Models

File Structure

docs/modules/orcaflex/jumper/<model>/
├── monolithic/          # Sanitized original OrcaFlex YAML
│   ├── DZ_AHCoff.yml
│   ├── SZ.yml
│   └── ...
└── spec.yml             # Extracted spec for modular builder

Commands

Generate from spec

uv run python -m digitalmodel.solvers.orcaflex.modular_generator --spec docs/modules/orcaflex/jumper/manifold_to_plet/spec.yml

Validate round-trip

uv run python scripts/semantic_validate.py \
  --mono docs/modules/orcaflex/jumper/manifold_to_plet/monolithic/SZ.yml \
  --modular output/generated_model.yml

Run benchmark

uv run python scripts/benchmark_model_library.py --library-only --three-way --skip-mesh

Implementation Notes

• Jumper models use the generic field in ProjectInputSpec (not dedicated jumper schema)
• The MonolithicExtractor handles arbitrary OrcaFlex object types including 3DBuoys, 6DBuoys, Constraints, Winches
• Vessel RAO data round-trips through the extractor (verify RAO table sizes)
• ExternalFunction DLL references will cause benchmark failures — add to skip list
• For parametric studies, use the campaign generator pattern with seed/heading/Hs variations

Related Skills

• /orcaflex-extreme-analysis — General installation modelling
• /orcaflex-model-generator — Modular YAML generation from spec
• /orcaflex-modeling — Core OrcaFlex modelling patterns
• /orcaflex-specialist — Advanced OrcaFlex specialist workflows