scientimate.wavefrompressurezcross#

Hs, Ts, Hz, Tz, Hrms, H, T, Eta, t = scientimate.wavefrompressurezcross(P, fs, h, heightfrombed=0, Kpmin=0.15, kCalcMethod='beji', Rho=1000, dispout='no')

Description#

Calculate wave properties from water pressure by using an upward zero crossing method

Inputs#

P: Water pressure time series data in (N/m^2)
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)
Kpmin=0.15: Minimum acceptable value for a pressure response factor

If Kpmin=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
P=Eta*9.81*1000*(np.cosh(k*hfrombed)/np.cosh(k*h))
Hs,Ts,Hz,Tz,Hrms,H,T,Eta,t=sm.wavefrompressurezcross(P,fs,5,4,0.15,'beji',1025,'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.

scientimate.wavefrompressurezcross

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