swiift.api.spectra¶

Consistant implementations of usual spectral formulations.

Spectra are defined as function of the frequency. Definitions are taken from [1].

References

Classes¶

`PiersonMoskowitz`	Class encapsulating the Pierson--Moskowitz spectrum.
`Bretschneider`	Class encapsulating the Bretschneider spectrum.
`JONSWAP`	Class encapsulating the JONSWAP spectrum.

Module Contents¶

class swiift.api.spectra.PiersonMoskowitz¶

Bases: _PMFamily

Class encapsulating the Pierson–Moskowitz spectrum.

classmethod from_swh(swh, gravity)¶

Build a spectrum parameterised by the SWH.

Parameters:

swh (float) – Significant wave height, in m.
gravity (float) – Acceleration of gravity, in m s**-2.

Returns:

Initialised spectrum object.

Return type:

PiersonMoskowitz

classmethod from_peak_frequency(peak_frequency, gravity)¶

Build a spectrum parameterised by the peak frequency.

Parameters:

peak_frequency (float) – Peak frequency, in Hz.
gravity (float) – Acceleration of gravity, in m s^-2.

Returns:

Initialised spectrum object.

Return type:

PiersonMoskowitz

class swiift.api.spectra.Bretschneider¶

Bases: _PMFamily

Class encapsulating the Bretschneider spectrum.

classmethod from_peak_frequency_swh(peak_frequency, swh)¶

Build a spectrum parameterised by peak frequency and SWH.

Parameters:

peak_frequency (float) – Peak frequency, in Hz.
swh (float) – Significant wave height, in m.

Returns:

Initialised spectrum.

Return type:

Bretschneider

class swiift.api.spectra.JONSWAP¶

Bases: _UnimodalSpectrum

Class encapsulating the JONSWAP spectrum.

The JONSWAP spectrum modifies the PM spectrum by introducing a peak enhancement factor.

peakedness¶

Type:: float

_base_spectrum¶

Type:: PiersonMoskowitz

property peak_frequency: float¶

Peak frequency.

Returns:: Peak frequency, in Hz.
Return type:: float

swh()¶

Significant wave height.

The SWH is computed with a cubic approximation.

Returns:: Significant wave height, in m.
Return type:: float

classmethod from_parameters(peak_frequency, peakedness, gravity)¶

Build a spectrum.

Peak frequency and gravity are used to instantiate the underlying Pierson–Moskowitz spectrum, while peakedness is specific to the JONSWAP formulation.

Parameters:

peak_frequency (float) – Peak frequency, in Hz.
peakedness (float) – Peakedness (base of the peak enhancement factor).
gravity (float) – Acceleration of gravity, in m s^-2.

Returns:

Initialised spectrum.

Return type:

JONSWAP

density(frequency)¶

Spectral density as a function of frequency.

Parameters:: frequency (array_like) – Frequency at which to evaluate the density.
Returns:: density – The density in m^2 s.
Return type:: float or np.ndarray