orcawave-qtf-analysis

name	orcawave-qtf-analysis
description	Second-order wave force QTF computation in OrcaWave. Use when computing mean drift forces, difference-frequency or sum-frequency QTFs, slow-drift response, or applying Newman approximation for offshore structures.
type	reference
version	1.0.0
updated	"2026-01-17T00:00:00.000Z"
category	engineering
triggers	["QTF computation","quadratic transfer function","mean drift force","second order wave forces","difference frequency","sum frequency","slow drift","Newman approximation","full QTF"]
capabilities	[]
requires	[]
tags	[]
scripts_exempt	true

Orcawave Qtf Analysis

When to Use

• Computing mean drift forces for mooring analysis
• Generating full QTF matrices for slow-drift response
• Difference-frequency force calculation
• Sum-frequency force calculation (springing)
• Newman approximation vs full QTF comparison
• Deep water vs shallow water second-order effects
• Moored vessel slow-drift motion prediction

Python API

Basic QTF Computation

from digitalmodel.orcawave.qtf import OrcaWaveQTF

# Initialize QTF analysis
qtf = OrcaWaveQTF()

# Load OrcaWave model with first-order results
qtf.load_model("models/fpso.owr")

# Configure QTF computation

*See sub-skills for full details.*
### Full QTF Matrix Generation

```python
from digitalmodel.orcawave.qtf import FullQTFComputation

# Initialize full QTF computation
full_qtf = FullQTFComputation()

# Configure frequency pairs
full_qtf.configure(
    frequencies=np.linspace(0.02, 0.5, 25),  # rad/s
    heading_pairs=[

*See sub-skills for full details.*
### Newman Approximation

```python
from digitalmodel.orcawave.qtf import NewmanApproximation

# Initialize Newman approximation
newman = NewmanApproximation()

# Load first-order results
newman.load_first_order_results("results/fpso_raos.csv")

# Compute approximate QTF

*See sub-skills for full details.*
### Mean Drift Analysis

```python
from digitalmodel.orcawave.qtf import MeanDriftAnalyzer

# Initialize analyzer
drift = MeanDriftAnalyzer()

# Load OrcaWave results
drift.load_results("models/fpso.owr")



*See sub-skills  full details.*


```python
 digitalmodel.orcawave.qtf  SlowDriftResponse


slow_drift = SlowDriftResponse()


slow_drift.load_qtf()



*See sub-skills  full details.*



- [orcawave-analysis](../orcawave-analysis/SKILL.md) - First-order diffraction analysis
- [mooring-design](../mooring-design/SKILL.md) - Mooring system design
- [hydrodynamics](../hydrodynamics/SKILL.md) - Wave loading management
- [orcaflex/modeling](../orcaflex/modeling/SKILL.md) - Time-domain simulation



- Pinkster, J.A.: Low Frequency Second Order Wave Exciting Forces
- Newman, J.N.: Second-Order Wave Forces on a Vertical Cylinder
- Standing, R.G.: Low Frequency Wave Drift Forces
- OrcaWave QTF Documentation

---

**Version History**

- **** (-01-): Initial release  full QTF, Newman approximation,  slow drift analysis



- [When to Use Full QTF vs Newman (+)](when-to-use-full-qtf-vs-newman/SKILL.md)



- [Error Handling](error-handling/SKILL.md)



- [Version Metadata](version-metadata/SKILL.md)
- [Force Components (+)](force-components/SKILL.md)
- [QTF Analysis Configuration (+)](qtf-analysis-configuration/SKILL.md)
- [Available Data (+)](available-data/SKILL.md)
- [CLI Usage](cli-usage/SKILL.md)




OrcaWave topics (`data/llm-wiki/orcawave/`):
- `Data,QTFs.md` -- QTF computation configuration
- `Theory,Second-orderequations.md` -- second-order BVP theory
- `Results,Quadraticloads.md` -- QTF output (mean drift, full QTF matrices)
- `Results,Potentialloads.md` -- potential-based load results
- `Data,Environment.md` -- water depth affecting second-order effects

OrcaFlex topics (`data/llm-wiki/orcaflex/`):
- `Vesseltypes,WavedriftandsumfrequencyQTFs.md` -- QTF data  vessel types
- `Vesseltheory,Wavedriftandsumfrequencyloads.md` -- drift/-frequency theory
- `Modellingvesselslowdrift.md` -- slow drift modelling  OrcaFlex