WaveSpec.jl

Description

WaveSpec.jl is a Julia package for generating stochastic sea states using Airy wave theory, widely used in numerical ocean modeling and hydrodynamics. It provides a modular framework for defining, discretizing, and simulating ocean wave spectra.

The package allows users to:

1. Define continuous wave spectra (e.g., JONSWAP, TMA, Bretschneider).
2. Choose sampling strategies (e.g., Uniform, Logarithmic, Chebyshev) in either frequency or energy domains.
3. Apply angular spreading models (e.g., Cosine-Power, Von Mises).
4. Generate Airy wave states (amplitude, phase, frequency, direction) for time-domain reconstruction.

Key Features

Continuous Spectrums

Pre-defined spectral models with adjustable parameters:

• JONSWAP
• TMA (Finite depth)
• Bretschneider
• Donelan
• OchiHubble (Multi-modal)

Discretization & Sampling

Flexible discretization of continuous spectra:

• Domains: Frequency Domain (Frequency), Energy Domain (Energy).
• Methods: UniformSampling, LogSampling, ChebyshevSampling.
• DiscreteSpectralSpreading: Converts a continuous spectrum into discrete frequency bands.

Angular Spreading

Directional spreading models for realistic 3D seas:

• CosinePowerDistribution
• VonMisesDistribution
• DonelanBannerDistribution
• DiscreteAngularSpreading: Discretize directionality with a specified number of angles.

Wave Generation

• AiryState: Combines spectral and angular information into a complete sea state description.
• generate_sea: Generates time-series data using linear wave theory (Airy waves).

Installation

using Pkg
Pkg.add("WaveSpec")

Basic Usage

Here is a simple example of how to generate a classic JONSWAP sea state:

using WaveSpec

# 1. Define a JONSWAP spectrum
Hs = 2.5  # Significant wave height [m]
Tp = 8.0  # Peak period [s]
spec = JONSWAP(Hs, Tp)

# 2. Discretize the spectrum
# DiscreteSpectralSpreading(shape, strategy, fmin, fmax, nf; domain=Frequency)
discrete_spec = DiscreteSpectralSpreading(
    spec,
    LogSampling(),         # Sampling strategy
    0.05,                  # fmin [Hz]
    1.0,                   # fmax [Hz]
    50;                    # Number of frequencies
    domain = Frequency     # Sampling domain
)

# 3. Define Angular Spreading
# DiscreteAngularSpreading(dist::UnivariateDistribution, a::Real, b::Real, nθ::Int; units=:radians)
# Cosine-Power distribution centered at 0 radians with power exponent 2, truncated between -π/2 and π/2
angle_dist = CosinePowerDistribution(0.0, 2.0)
discrete_angle = DiscreteAngularSpreading(angle_dist, -π/2, π/2, 36) # 36 discrete angles

# 4. Generate the Sea State
depth = 50.0 # Water depth [m]
sea_state = AiryState(discrete_spec, discrete_angle, depth)

# 5. Access wave components
# sea_state.ω (frequencies), sea_state.k (wavenumbers), sea_state.θ (angles)

Documentation

For full documentation, please visit the documentation website.

Contact

Please contact the main developers Shagun Agarwal, Pau Manyer or Oriol Colomés for further questions.