scientimate.wavefromvelocityzcross#
Hs, Ts, Hz, Tz, Hrms, H, T, Eta, t = scientimate.wavefromvelocityzcross(Ux, Uy, fs, h, heightfrombed=0, Kuvmin=0.15, kCalcMethod='beji', dispout='no')
Description#
Calculate wave properties from wave orbital velocity by using an upward zero crossing method
Inputs#
- Ux
Wave horizontal orbital velocity data in x direction in (m/s)
- Uy
Wave horizontal orbital velocity data in y direction in (m/s)
- fs
Sampling frequency that data collected at in (Hz)
- h
Water depth in (m)
- heightfrombed=0
Height from bed that data collected at in (m)
- Kuvmin=0.15
- Minimum acceptable value for an orbital velocity converstion factorIf Kuvmin=0.15, it avoid wave amplification larger than 6 times (1/0.15)
- kCalcMethod=’beji’
- Wave number calculation method‘hunt’: Hunt (1979), ‘beji’: Beji (2013), ‘vatankhah’: Vatankhah and Aghashariatmadari (2013)‘goda’: Goda (2010), ‘exact’: calculate exact value
- Rho=1000
Water density (kg/m^3)
- dispout=’no’
Define to display outputs or not (‘yes’: display, ‘no’: not display)
Outputs#
- Hs
Significant Wave Height (m)
- Ts
Significant Wave Period (second)
- Hz
Zero Crossing Mean Wave Height (m)
- Tz
Zero Crossing Mean Wave Period (second)
- Hrms
Root Mean Square Wave Height (m)
- H
Wave Height Data Series array (m)
- T
Wave Period Data Series array (second)
- Eta
Water surface elevation time series in (m)
- t
Time (s)
Examples#
import scientimate as sm
import numpy as np
import scipy as sp
from scipy import signal
fs=2 #Sampling frequency
duration=1024 #Duration of the data
N=fs*duration #Total number of points
df=fs/N #Frequency difference
dt=1/fs #Time difference, dt=1/fs
t=np.linspace(0,duration-dt,N) #Time
Eta=sp.signal.detrend(0.5*np.cos(2*np.pi*0.2*t)+(-0.1+(0.1-(-0.1)))*np.random.rand(N))
hfrombed=4
h=5
k=0.2
Ux=(np.pi/5)*(2*Eta)*(np.cosh(k*hfrombed)/np.sinh(k*h))
Uy=0.2*Ux
Hs,Ts,Hz,Tz,Hrms,H,T,Eta,t=sm.wavefromvelocityzcross(Ux,Uy,fs,5,4,0.15,'beji','yes')
References#
Beji, S. (2013). Improved explicit approximation of linear dispersion relationship for gravity waves. Coastal Engineering, 73, 11-12.
Goda, Y. (2010). Random seas and design of maritime structures. World scientific.
Hunt, J. N. (1979). Direct solution of wave dispersion equation. Journal of the Waterway Port Coastal and Ocean Division, 105(4), 457-459.
Vatankhah, A. R., & Aghashariatmadari, Z. (2013). Improved explicit approximation of linear dispersion relationship for gravity waves: A discussion. Coastal engineering, 78, 21-22.