Last updated on Sep 04, 2024.

netsse.analys.enc_spec.resp_spec_2d#

netsse.analys.enc_spec.resp_spec_2d(freq0, mu, ws0, beta_TRF, TRF1, TRF2, freqE, U, psi, conv='from', unit_freq='rad/s')#

Computes a response cross-spectrum in the encounter-frequency domain, in a case of short-crested seas.

Note

This is a Python implementation of the algorithm given in Nielsen et al. (2021).

Parameters:

freq0 (array_like of shape (Nf0,)) – Vector of absolute frequencies, in which the wave spectrum and the transfer functions are expressed.
mu (array_like of shape (Nmu,)) – Vector of wave directions [deg], relative to North (in a NED-reference frame).
ws0 (array_like of shape (Nf0,Nmu) in 2-D) – 2-D wave spectrum, as a function of (absolute) wave frequency freq0 and wave direction mu [rad].
beta_TRF (array_like of shape (Nbeta,)) – Vector of relative wave headings [deg], in which the transfer functions are expressed.
TRF1 (array_like of shape (Nf0,Nbeta)) – Transfer function of the first and second response component, respectively, as a function of frequency freq0 and relative wave heading.
TRF2 (array_like of shape (Nf0,Nbeta)) – Transfer function of the first and second response component, respectively, as a function of frequency freq0 and relative wave heading.
freqE (array_like of shape (Nfe,)) – Vector of encounter frequencies for the output response spectrum.
U (float) – Ship speed [m/s]
psi (float) – Ship heading [deg], relative to North (in a NED-reference frame).
conv ({'from','to'}, optional) –
The convention that is used to express the direction mu of wave spectrum:
- ’from’ :
  The naval architecture convention, indicating where the waves are COMING FROM.
- ’to’ :
  The oceanographic convention, indicating where the waves are GOING TO. The default is “from” direction.
unit_freq ({'rad/s','Hz'}, optional) –
Unit of the frequencies:
- ’rad/s’ :
  The variables freq0 and freqE denote the angular frequencies in radians per second.
- ’Hz’ :
  The 2-D wave spectrum ws0 is expressed as a function of frequency in Hertz. The default is ‘rad/s’.

Returns:

RspecEnc – Response spectrum, as a function of encounter frequency freqE.

Return type:

array_like of shape (Nfe,)