viv-analysis

name	viv-analysis
description	Assess vortex-induced vibration (VIV) for risers and tubular members with natural frequency and safety factor calculations. Use for VIV susceptibility analysis, natural frequency calculation, vortex shedding assessment, and tubular member fatigue from VIV.
type	reference
updated	2026-01-07
capabilities	[]
requires	[]
tags	[]
scripts_exempt	true
category	engineering
version	1.0.0

Viv Analysis

When to Use

• VIV analysis for risers and pipelines
• Natural frequency calculation for tubular members
• Vortex shedding frequency analysis
• VIV fatigue damage assessment
• Tubular member VIV screening
• Safety factor evaluation against VIV criteria

Prerequisites

• Python environment with digitalmodel package installed
• Member geometry and material properties
• Current velocity profiles
• For risers: tension distribution along length

Python API

Natural Frequency Calculation

from digitalmodel.subsea.viv_analysis.viv_analysis import VIVAnalysis
from digitalmodel.subsea.viv_analysis.viv_tubular_members import VIVTubularMembers

# Initialize analysis
viv = VIVAnalysis()

# Define member properties
member = {
    "length": 50.0,

*See sub-skills for full details.*
### Vortex Shedding Analysis

```python
# Vortex shedding frequency
diameter = 0.5  # meters
current_velocity = 1.5  # m/s
strouhal = 0.2

shedding_freq = viv.vortex_shedding_frequency(
    diameter=diameter,
    velocity=current_velocity,
    strouhal_number=strouhal

*See sub-skills for full details.*
### Tubular Member Analysis

```python
from digitalmodel.subsea.viv_analysis.viv_tubular_members import VIVTubularMembers

# Initialize tubular member analysis
tubular = VIVTubularMembers()

# Define member
member_props = {
    "name": "Brace1",
    "outer_diameter": 0.324,

*See sub-skills for full details.*
### VIV Fatigue Assessment

```python
from digitalmodel.subsea.viv_analysis.viv_fatigue  VIVFatigue


viv_fatigue = VIVFatigue()


stress_range = viv_fatigue.calculate_stress_range(
    amplitude=,  
    diameter=,

*See sub-skills  full details.*



| Class | Purpose |
|-------|---------|
| `VIVAnalysis` | Main VIV analysis router |
| `VIVTubularMembers` | Tubular member assessment |
| `VIVAnalysisComponents` | Component-level analysis |
| `VIVFatigue` | VIV-induced fatigue damage |



- [catenary-riser](../catenary-riser/SKILL.md) - Riser configuration
- [fatigue-analysis](../fatigue-analysis/SKILL.md) - VIV fatigue damage
- [structural-analysis](../structural-analysis/SKILL.md) - Stress verification



- DNV-RP-C205: Environmental Conditions  Environmental Loads
- DNV-RP-F105: Free Spanning Pipelines
- Blevins, R.D.: Flow-Induced Vibration



- [Best Practices](best-practices/SKILL.md)



- [Version Metadata](version-metadata/SKILL.md)
- [[] - -01-07](--01-07/SKILL.md)
- [ Natural Frequency Analysis (+)](-natural-frequency-analysis/SKILL.md)
- [Strouhal Number (+)](strouhal-number/SKILL.md)
- [Complete VIV Screening Workflow](complete-viv-screening-workflow/SKILL.md)
- [Natural Frequencies JSON (+)](natural-frequencies-json/SKILL.md)
- [Design Code References](design-code-references/SKILL.md)