Maneuvering and Seakeeping Basin Wave Characterization Study

2017 ◽  
Author(s):  
Miguel Quintero ◽  
Samantha Lee
Keyword(s):  
Spatial Variability ◽  
Deep Trench ◽  
Wave Condition ◽  
Wave Statistics ◽  
Wave Parameters ◽  
Characterization Study ◽  
Series Of Experiments ◽  
Directional Wave ◽  
Fixed Array ◽  
Naval Surface Warfare

A series of experiments aimed at characterizing the wavefield generated by the new multi-directional wave making system in the Maneuvering and Seakeeping (MASK) Basin at the Naval Surface Warfare Center Carderock Division in West Bethesda, MD are described. These experiments were focused on the repeatability of phase resolved seaways, the spatial variability of wave parameters throughout the basin, and the stationarity of the wavefield over the span of 2 hours. Two different wave spectra were run repeatedly over a two week test window covering 21 discrete locations with one fixed array of sensors as a control. The results from the test show that when sampling at the same location and running the same wave condition, the phase resolved seaway exhibits a coherence of over 95% between 0.25 and 0.75 Hz. The spatial variability of the wave statistics proved to be within 5% of the average values throughout the tank, with a larger deviation over the 35ft deep trench section.

Estimation of Onsite Wave Parameters From the WindFloat Platform

2013 ◽  
Author(s):  
Antoine Peiffer ◽  
Nathan Tom ◽  
Christian Cermelli ◽  
Dominique Roddier
Keyword(s):  
Wave Spectra ◽  
Wave Direction ◽  
Wave Statistics ◽  
Wave Measurements ◽  
Wave Parameters ◽  
Floating Foundation ◽  
Wave Elevation ◽  
Many Instruments ◽  
Directional Wave ◽  
Buoy Measurements

The WindFloat is a semi-submersible floating foundation supporting multi-megawatt wind turbines. A full-scale 2MW WindFloat demonstration unit was installed off the coast of Portugal in October 2011. Many instruments are installed on this prototype to measure the environmental conditions and the response of the platform at the site. The first section of the paper focuses on the validation of the wave measurements obtained from two radar-based wave probes onboard the platform. The wave elevation at the site is reconstructed and typical wave statistics are computed. The results are compared and validated with independent buoy measurements close to site. The second section of the paper presents estimates of prevailing wave direction and directional wave spectra based on platform motions. These results are also benchmarked with onsite buoy measurements.

Simulation of Hurricane Seas in a Multidirectional Wave Basin

1991 ◽  
Vol 113 (3) ◽  
pp. 219-227 ◽  
Author(s):  
A. Cornett ◽  
M. D. Miles
Keyword(s):  
Ocean Waves ◽  
Entropy Method ◽  
Wave Spectra ◽  
Single Wave ◽  
Wave Condition ◽  
Wave Basin ◽  
Wide Range ◽  
Directional Wave ◽  
Wave Conditions ◽  
Multidirectional Wave

This paper describes the generation and verification of four realistic sea states in a multidirectional wave basin, each representing a different storm wave condition in the Gulf of Mexico. In all cases, the degree of wave spreading and the mean direction of wave propagation are strongly dependent on frequency. Two of these sea states represent generic design wave conditions typical of hurricanes and winter storms and are defined by JONSWAP wave spectra and parametric spreading functions. Two additional sea states, representing the specific wave activity during hurricanes Betsy and Carmen, are defined by tabulated hindcast estimates of the directional wave energy spectrum. The Maximum Entropy Method (MEM) of directional wave analysis paired with a single-wave probe/ bi-directional current meter sensor is found to be the most satisfactory method to measure multidirectional seas in a wave basin over a wide range of wave conditions. The accuracy of the wave generation and analysis process is verified using residual directional spectra and numerically synthesized signals to supplement those measured in the basin. Reasons for discrepancy between the measured and target directional wave spectra are explored. By attempting to reproduce such challenging sea states, much has been learned about the limitations of simulating real ocean waves in a multidirectional wave basin, and about techniques which can be used to minimize the associated distortions to the directional spectrum.

Variations in directional wave parameters obtained from data measured using a GNSS buoy

2020 ◽  
Vol 209 ◽  
pp. 107513
Author(s):  
Yen-Pin Lin ◽  
Ching-Jer Huang ◽  
Sheng-Hsueh Chen
Keyword(s):  
Wave Parameters ◽  
Directional Wave

Effect of intrinsic and sampling variability on wave parameters and wave statistics

2014 ◽  
Vol 64 (11) ◽  
pp. 1643-1655 ◽  
Author(s):  
Elzbieta M. Bitner-Gregersen ◽  
Anne Karin Magnusson
Keyword(s):  
Sampling Variability ◽  
Wave Statistics ◽  
Wave Parameters

scholarly journals Research on the Algorithm Model for Measuring Ocean Waves Based on Satellite GPS Signals in China

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 541 ◽  
Author(s):  
Zhanhui Qi ◽  
Shaowu Li ◽  
Mingbing Li ◽  
Chaoqun Dang ◽  
Dongbo Sun ◽  
...  
Keyword(s):  
Wave Spectrum ◽  
Ocean Wave ◽  
Acquisition Time ◽  
Measurement Technology ◽  
Movement Velocity ◽  
Wave Parameters ◽  
Wave Measurement ◽  
Improvement Measures ◽  
Directional Wave ◽  
Gravity Acceleration

In recent years, the GPS wave buoy has been developed for in situ wave monitoring based on satellite GPS signals. Many research works have been completed on the GPS-based wave measurement technology and great progress has been achieved. The basic principle of the GPS wave buoy is to calculate the movement velocity of the buoy using the Doppler frequency shift of satellite GPS signals, and then to calculate the wave parameters from the movement velocity according to ocean wave theory. The shortage of the GPS wave buoy is the occasional occurrence of some unusual values in the movement velocity. This is mainly due to the fact that the GPS antenna is occasionally covered by sea water and cannot normally receive high-quality satellite GPS signals. The traditional solution is to remove these unusual movement velocity values from the records, which requires furthering extend the acquisition time of satellite GPS signals to ensure there is a large enough quantity of effective movement velocity values. Based on the traditional GPS wave measurement technology, this paper presents the algorithmic flow and proposes two improvement measures. On the one hand, the neural network algorithm is used to correct the unusual movement velocity data so that extending the acquisition time of satellite GPS signals is not necessary and battery power is saved. On the other hand, the Gaussian low-pass filter is used to correct the raw directional wave spectrum, which can further eliminate the influence of noise spectrum energy and improve the measurement accuracy. The on-site sea test of the SBF7-1A GPS wave buoy, developed by the National Ocean Technology Center in China, and the gravity-acceleration-type DWR-MKIII Waverider buoy are highlighted in this article. The wave data acquired by the two buoys are analyzed and processed. It can be seen from the processed results that the ocean wave parameters from the two kinds of wave buoys, such as wave height, wave period, wave direction, wave frequency spectrum, and directional wave spectrum, are in good consistency, indicating that the SBF7-1A GPS wave buoy is comparable to the traditional gravity-acceleration-type wave buoy in terms of its accuracy. Therefore, the feasibility and validity of the two improvement measures proposed in this paper are confirmed.

Numerical Study of Wave Climate in Jiangsu Sea Area

2014 ◽  
Vol 501-504 ◽  
pp. 2099-2106
Author(s):  
Liang Ding ◽  
Fei Fan ◽  
Jia Rui Li
Keyword(s):  
Wave Height ◽  
Flow Model ◽  
Numerical Study ◽  
Wave Model ◽  
Wave Climate ◽  
Wave Condition ◽  
Wave Parameters ◽  
Average Wave ◽  
Buoy Data ◽  
Sea Area

This paper studied the wave condition of Jiangsu Sea area with wave model SWAN, which was driven by the wind field from 1990.01.01 to 2011.12.30. Firstly, tidal current of Jiangsu sea area was simulated by the Delft3D flow model. Then, wave parameters of East China Sea and Jiangsu sea area were computed, and then buoy data was used to compared with the modeled, they validated well. Last, the average wave height and period are calculated, and the distribution of wave height on each direction was studied. The result shows that the largest annually average wave height of Jiangsu is up to 1.6m. The average wave height is decreasing from southeast to northwest. The wave height in winter is larger than other seasons. In this sea area, waves mainly come from NE and SE directions. Strong waves come from NE or NNE direction.

Observations and Modeling of Linear and Nonlinear Spatio-Temporal Wave Statistics

2010 ◽  
Author(s):  
Leonel Romero ◽  
W. Kendall Melville
Keyword(s):  
Spatial Information ◽  
Second Order ◽  
Stochastic Simulations ◽  
Ocean Engineering ◽  
Engineering Applications ◽  
Large Wave ◽  
Wave Statistics ◽  
Wave Parameters ◽  
Wave Heights ◽  
Spatio Temporal

We present an analysis of airborne wave observations collected in the Gulf of Tehuantepec. The data includes LIDAR measurements of the surface displacement as a function of two horizontal dimensions and time in fetch-limited conditions, with fetches between 50 and 300 km and winds between 10 and 20 m/s. The spatio-temporal data have an advantage over the commonly used single point time-series measurements allowing direct estimates of the wavelength and wave slope, including spatial information such as the lengths of crests exceeding threshold wave heights and slopes. The statistics of these wave parameters are particularly important for risk assessment of off-shore structures and in other ocean engineering applications. We present an analysis of several statistical wind-wave parameters, including the joint probability distribution function (pdf) of wave amplitudes and wavelengths, the pdf of wave heights, wavenumber vectors, and wave slopes, including the statistics of crests lengths exceeding threshold wave heights or slopes. The empirical findings from the LIDAR data are related to the analytical work by Longuet-Higgins (1957) [1] for a linear spectrum, including the average length of contours surrounding large wave heights. The effect of second-order nonlinearities on the distribution of crest lengths is investigated with numerical stochastic simulations from computed directional wavenumber spectra. The results show that second-order nonlinearities can increase the crest length density of large waves by about a factor of two or more. The results are discussed in the context of predicting wave statistics for ocean engineering applications.

Comparison of Temporal and Spatial Statistics of Nonlinear Waves

2019 ◽  
Author(s):  
Elzbieta M. Bitner-Gregersen ◽  
Odin Gramstad
Keyword(s):  
Spatial Statistics ◽  
Modulational Instability ◽  
Rogue Waves ◽  
Nonlinear Dynamical ◽  
Wave Statistics ◽  
Wave Data ◽  
Camera Systems ◽  
Wave Parameters ◽  
Temporal And Spatial ◽  
Numerical Solver

Abstract In the past, it was most common to derive wave parameters and their statistics from time series of wave elevation. The duration of the wave records has been usually restricted to 20 or 30 minutes. Recently, increasing attention has started to be given to spatial wave data and wave statistics, particularly due to introduction in oceanography of stereo camera systems for collecting space–time ensemble of sea surface elevation. Using numerical linear, 2nd and 3rd order simulations this study compares temporal and spatial statistics of wave parameters. The 3rd order wave data are simulated by a numerical solver based on the Higher Order Spectral Method (HOSM) which includes the leading order nonlinear dynamical effects, accounting for the effect of modulational instability. The Pierson-Moskowitz and the JONSWAP spectrum with different gamma parameters are used in the analysis. Sea states with wave steepness where rogue waves were recorded in nature are considered. Consequences of using temporal contra spatial statistics are discussed in perspective of marine structures’ design. Functional dependency between wave parameters characterizing occurrence of rogue waves in unidirectional wave field is proposed.

Comparison Of Norcsex'88 CV-580 Sar, Wavescan Buoy, And Numerical Wave Model Directional Wave Parameters

2005 ◽  
Author(s):  
J.P. Pedersen ◽  
T. Guneriussen ◽  
H. Johnsen ◽  
K.A. Hogda ◽  
P. Wind
Keyword(s):  
Wave Model ◽  
Wave Parameters ◽  
Directional Wave ◽  
Numerical Wave

scholarly journals ON THE INVESTIGATION OF WIND GENERATED WAVES IN BANGLADESH RIVERS FOR THE ASSESSMENT OF STABILITY REQUIREMENTS IN INLAND VESSEL DESIGN

Brodogradnja ◽  
2021 ◽  
Vol 72 (3) ◽  
pp. 45-59
Author(s):  
Muhammad Rabiul Islam ◽  
◽  
Mahmudul Hasan Akib ◽  
Fariha Tabassum ◽  
Khandakar Akhter Hossain
Keyword(s):  
Failure Modes ◽  
Ocean Waves ◽  
Secondary Source ◽  
Short Term ◽  
Wave State ◽  
Safety Level ◽  
Wave Condition ◽  
Inland River ◽  
Wave Parameters ◽  
Wind Velocities

Standard environmental condition is one of the main inputs in designing a vessel especially in assessment of stability condition. The performance based minimum stability requirements are determined by assessing vessels' dynamic failure modes. Winds as well as wind generated waves are the main factors that affect a specific vessel’s dynamics. Wind generated waves in rivers though are usually small in comparison with ocean waves may play a crucial role behind inland vessels accidents. The river condition of a crucial location in Bangladesh inland river routes is assessed where wind velocities have been taken for a specific duration from a reliable secondary source. A narrow fetch model that considers the wave generation in off-wind direction for estimating wind wave parameters has been used to consider the spiral shape of Bangladesh inland routes. The Bretschneider energy spectrum model for short term wave state is compared with the fetch limited model JONSWAP for the estimated wave condition. This study indicates the rationality of conforming the safety level of Bangladesh inland vessels equivalent to river-sea vessels as defined by other nationals and the classification societies. The wave parameters that are estimated in this study can be used to form a limited wave scatter table for predicting short term environmental conditions to assess the dynamic stability failure modes of the vessels.

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