scholarly journals Managing Information Uncertainty in Wave Height Modeling for the Offshore Structural Analysis through Random Set

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Keqin Yan ◽  
Yi Zhang ◽  
Tao Cheng ◽  
Xianfeng Luo ◽  
Quan Zhou ◽  
...  
Keyword(s):  
Wave Height ◽  
Probabilistic Models ◽  
Pushover Analysis ◽  
Probabilistic Approach ◽  
Wave Model ◽  
Information Uncertainty ◽  
Random Waves ◽  
Random Set ◽  
Wave Direction ◽  
Base Shear

This chapter presents a reliability study for an offshore jacket structure with emphasis on the features of nonconventional modeling. Firstly, a random set model is formulated for modeling the random waves in an ocean site. Then, a jacket structure is investigated in a pushover analysis to identify the critical wave direction and key structural elements. This is based on the ultimate base shear strength. The selected probabilistic models are adopted for the important structural members and the wave direction is specified in the weakest direction of the structure for a conservative safety analysis. The wave height model is processed in a P-box format when it is used in the numerical analysis. The models are applied to find the bounds of the failure probabilities for the jacket structure. The propagation of this wave model to the uncertainty in results is investigated in both an interval analysis and Monte Carlo simulation. The results are compared in context of information content and numerical accuracy. Further, the failure probability bounds are compared with the conventional probabilistic approach.

scholarly journals On the Sensitivity of Typhoon Wave Simulations to Tidal Elevation and Current

2020 ◽  
Vol 8 (9) ◽  
pp. 731 ◽  
Author(s):  
Shih-Chun Hsiao ◽  
Han-Lun Wu ◽  
Wei-Bo Chen ◽  
Chih-Hsin Chang ◽  
Lee-Yaw Lin
Keyword(s):  
Wave Height ◽  
Tidal Current ◽  
Outer Region ◽  
Wave Model ◽  
Tidal Currents ◽  
Integrated System ◽  
Wave Direction ◽  
Wind Fields ◽  
Tidal Elevation ◽  
Typhoon Wave

The sensitivity of storm wave simulations to storm tides and tidal currents was investigated using a high-resolution, unstructured-grid, coupled circulation-wave model (Semi-implicit Cross-scale Hydroscience Integrated System Model Wind Wave Model version III (SCHISM-WWM-III)) driven by two typhoon events (Typhoons Soudelor and Megi) impacting the northeastern coast of Taiwan. Hourly wind fields were acquired from a fifth-generation global atmospheric reanalysis (ERA5) and were used as meteorological conditions for the circulation-wave model after direct modification (MERA5). The large typhoon-induced waves derived from SCHISM-WWM-III were significantly improved with the MERA5 winds, and the peak wave height was increased by 1.0–2.0 m. A series of numerical experiments were conducted with SCHISM-WWM-II and MERA5 to explore the responses of typhoon wave simulations to tidal elevation and current. The results demonstrate that the simulated significant wave height, mean wave period and wave direction for a wave buoy in the outer region of the typhoon are more sensitive to the tidal current but less sensitive to the tidal elevation than those for a wave buoy moored in the inner region of the typhoon. This study suggests that the inclusion of the tidal current and elevation could be more important for typhoon wave modeling in sea areas with larger tidal ranges and higher tidal currents. Additionally, the suitable modification of the typhoon winds from a global atmospheric reanalysis is necessary for the accurate simulation of storm waves over the entire region of a typhoon.

scholarly journals Wave run-up on embayed beaches. Study case: Itapocorói Bay, Southern Brazil

2017 ◽  
Vol 65 (2) ◽  
pp. 187-200 ◽  
Author(s):  
Guilherme Vieira da Silva ◽  
Paula Gomes da Silva ◽  
Rafael Sangoi Araujo ◽  
Antonio Henrique da Fontoura Klein ◽  
Elírio E. Toldo Jr.
Keyword(s):  
Wave Height ◽  
Wave Model ◽  
Swash Zone ◽  
Southern Brazil ◽  
Wave Direction ◽  
Linear Processes ◽  
Similarity Parameter ◽  
Peak Period ◽  
The Mean ◽  
Run Up

ABSTRACT This paper presents a new approach for estimating run-up on embayed beaches based on a study of the microtidal coast of Itapocorói Bay, Southern Brazil using the surf similarity parameter and wave height at break location. The four step methodology involved: 1) direct wave measurement (34 days), wave run-up measurement (19 days at 7 points within the bay), measurement of bathymetry and beach topography in the entire bay; 2) tests on available formulae to calculate wave run-up; 3) use of the SWAN spectral wave model to simulate wave parameters at breaking at each wave run-up measurement point and; 4) development of a new formula/approach to assess wave run-up on embayed beaches (in both exposed and protected areas). During the experiments the significant wave height varied from 0.5 m to 3.01 m, the mean wave period from 2.79 s to 7.76 s (the peak period varied between 2.95 s and 17.18 s), the mean wave direction from 72.5° to 141.9° (the peak direction varied from 39.2° to 169.8°) and the beach slope (tan β) from 0.041 to 0.201. The proposed formula is in good agreement with measured data for different wave conditions and varying degrees of protection. The analysis demonstrates that although R² varies from 0.52 to 0.75, the wave run-up distribution over the measurements agreed well with the proposed model, as shown by quantile-quantile analysis (R²=0.98 to 0.99). The errors observed in individual cases may be related to errors of measurements, modeling and to non-linear processes in the swash zone, such as infragavity waves.

scholarly journals Sea State Determination from Ship-Based Geodetic GPS

2014 ◽  
Vol 31 (11) ◽  
pp. 2556-2564 ◽  
Author(s):  
James Foster ◽  
Ning Li ◽  
Kwok Fai Cheung
Keyword(s):  
Wave Height ◽  
Wave Model ◽  
Ocean Waves ◽  
Sea Surface ◽  
Wave Direction ◽  
Sea State ◽  
Dominant Wave ◽  
Model Predictions ◽  
Economic Vitality ◽  
Buoy Data

AbstractOcean waves have a profound impact on navigation, offshore operations, recreation, safety, and the economic vitality of a nation’s maritime and coastal communities. This study demonstrates that ships equipped with geodetic GPS and a radar gauge can provide accurate estimates of sea state. The Research Vessel (R/V) Kilo Moana recorded 1-Hz data for the entire period of a 10-day cruise around the Hawaiian Islands. Solving for precise kinematic positions for the ship and combining these solutions with the ranges from the ship to the sea surface provided by the radar gauge, it was possible to retrieve 1-Hz estimates of the sea surface elevation along the cruise track. Converting these into estimates of significant wave height, strong agreement was found with wave buoy measurements and hindcast wave data. Comparison with buoy data indicates the estimates have errors on the order of 0.22 m, or less than 11% of the wave height. Using wave model predictions of the dominant directions, the data were processed further to correct for the Doppler shift and to estimate the dominant wave period. Although relatively noisy in locations where the predicted wave directions are expected to be poor, in general these estimates also show a good agreement with the wave buoy observations and hindcast wave estimates. A segment of the cruise that formed a circuit allowed for testing the consistency of the ship-based estimates and for determining a dominant wave direction, which was found to agree closely with model predictions.

scholarly journals Global ship accidents and ocean swell-related sea states

2017 ◽  
Vol 17 (11) ◽  
pp. 2041-2051 ◽  
Author(s):  
Zhiwei Zhang ◽  
Xiao-Ming Li
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Environmental Issues ◽  
Wave Model ◽  
Economic Losses ◽  
Wave Direction ◽  
Sea State ◽  
Mean Wave Period ◽  
Numerical Wave ◽  
Wind Sea

Abstract. With the increased frequency of shipping activities, navigation safety has become a major concern, especially when economic losses, human casualties and environmental issues are considered. As a contributing factor, the sea state plays a significant role in shipping safety. However, the types of dangerous sea states that trigger serious shipping accidents are not well understood. To address this issue, we analyzed the sea state characteristics during ship accidents that occurred in poor weather or heavy seas based on a 10-year ship accident dataset. Sea state parameters of a numerical wave model, i.e., significant wave height, mean wave period and mean wave direction, were analyzed for the selected ship accident cases. The results indicated that complex sea states with the co-occurrence of wind sea and swell conditions represent threats to sailing vessels, especially when these conditions include similar wave periods and oblique wave directions.

scholarly journals Assessing the Performance of the Dissipation Parameterizations in WAVEWATCH III Using Collocated Altimetry Data

2009 ◽  
Vol 39 (11) ◽  
pp. 2800-2819 ◽  
Author(s):  
Georgia D. Kalantzi ◽  
Christine Gommenginger ◽  
Meric Srokosz
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Source Term ◽  
Wave Spectrum ◽  
Wave Model ◽  
North Indian Ocean ◽  
Altimeter Data ◽  
Wave Direction ◽  
Wavewatch Iii ◽  
The North

Abstract Wave-breaking dissipation is one of the least understood processes implemented in contemporary wave models. Significant effort has been put in its parameterization, but it has not proven to be totally satisfactory, either theoretically or practically. In this work, the WAVEWATCH III (version 2.22; Tolman) wave model is used to evaluate the two wind input/dissipation source term packages that it includes: (i) Wave Model (WAM) cycle 3 (WAMDIG) and (ii) Tolman and Chalikov. Global model outputs were obtained under the same wind forcing for the two dissipation formulations and were collocated in space and time in the north Indian Ocean with Ocean Topography Experiment (TOPEX) altimeter data. The performance of the model was assessed by evaluating the statistical behavior of the collocated datasets. The parameters examined were significant wave height, wind speed, wind direction, wave direction, wave height for fully developed seas, and energy loss due to wave breaking. From the results, the behavior of the input/dissipation formulations in specific wind and wave conditions was identified; that is, the results give insight to the way the two source term packages “work” and how they respond to local wind sea or swell. Specifically, both of the packages were unable to perform adequately during a season when the area can be mostly affected by swell. However, the results confirmed that the examination of only integral spectral wave parameters does not give information on the inherent physical characteristics of the formulations. Further study, on the basis of point spectra, is necessary to examine the formulations’ performance across the wave spectrum.

Comparing Nearshore Wave Parameters in Amurang Bay location using MIKE-21 Spectral Wave Model

2019 ◽  
Vol 1 (2) ◽  
pp. 150-158
Author(s):  
Tommy Jansen
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Model ◽  
Google Earth ◽  
Coastal Development ◽  
Wave Direction ◽  
Wet Season ◽  
Significant Wave ◽  
Wave Parameters ◽  
Mike 21

Wave parameters as an accurate prediction in ocean environment are important thing for good coastal development. Spectral wind wave model as a tools in MIKE 21 SW based on unstructured mesh is used in this study which the model simulates the growth, decay and transformation of wind generated waves and swell in offshore and coastal areas. The Amurang Bay as the province of North Sulawesi Indonesia was selected as the study area which the geography position around 1012’16.16” N-124027’04.33” E to 1015’43.80” N-124032’01.06”E. The bathymetry and tide data used in this research from Indonesian Coastline Environmental map of year 1995 with scale 1:50.000 from BIG (Badan Informasi Geospasial) with a satellite data from Google earth of year 2018 and LANTAMAL Manado, the wind and current data was obtained from BMKG Manado. Time simulations are taken from 25 November to 23 December 2016 as a wet season and 25 Mei to 23 June 2016 as a dry season.The model computed the wave parameters using the forecast wind input. The synoptic map of significant wave height (Hs), wave period, wave direction are obtained from the result of simulation. During the dry and wet season conditions the predicted wave parameters as the result of the simulation with tide and wind show to be higher than with tide and no wind simulation. The average condition of significant wave height is higher in outside of bay than inside of bay.

scholarly journals Experimental Investigation of Wave Height Changes on the Base Shear and Overturning Moment of the Jacket Subjected to Random Waves in Deep Waters

2019 ◽  
Vol 10 (40) ◽  
pp. 19-28
Author(s):  
Arash Dalili Osgouei ◽  
Ramin Vafaei Poursorkhabi ◽  
Ahmad Maleki ◽  
Hamid Ahmadi ◽  
◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Wave Height ◽  
Random Waves ◽  
Base Shear ◽  
Deep Waters ◽  
Overturning Moment

The Concept of the Optimum Alignment of Discharge Pipelines Due to the Minimization of the Wave Forces

1992 ◽  
Vol 25 (9) ◽  
pp. 211-216
Author(s):  
A. Akyarli ◽  
Y. Arisoy
Keyword(s):  
Wave Height ◽  
Wave Force ◽  
Wave Forces ◽  
Wave Direction ◽  
Incoming Wave ◽  
Pipeline Route ◽  
Optimum Alignment ◽  
The Cost ◽  
Resultant Wave

As the wave forces are the function of the wave height, period and the angle between the incoming wave direction and the axis of the discharge pipeline, the resultant wave force is directly related to the alignment of the pipeline. In this paper, a method is explained to determine an optimum pipeline route for which the resultant wave force becomes minimum and hence, the cost of the constructive measures may decrease. Also, the application of this method is submitted through a case study.

Application of Wave Devouring Propulsion System for Ocean Engineering

2013 ◽  
Author(s):  
Yutaka Terao ◽  
Norimitsu Sakagami
Keyword(s):  
Data Acquisition ◽  
Wave Height ◽  
Autonomous Navigation ◽  
Data Acquisition System ◽  
Propulsion System ◽  
Acquisition System ◽  
Wave Power ◽  
Wave Direction ◽  
Ocean Engineering ◽  
Damping Force

A Wave Devouring Propulsion System (WDPS) generates thrust directly from wave power while simultaneously generating a strong damping force. A simple WDPS design consists of hydrofoils mounted below the bow of a vessel. If a WDPS is integrated with the hull of a vessel, then it can power the vessel forward, even against the wave direction itself. One example of a successful WDPS was installed on the vessel named Mermaid II, which completed a trans-Pacific voyage in 2008, traveling approximately 7,800 km from Hawaii to Japan using wave power alone. This success indicates that the WDPS has potential for use in the field of ocean engineering. As described in this paper, we intend to apply the WDPS to the small autonomous boat and to conduct sea trials. We designed and built an autonomous WDPS boat, developed a data acquisition system, and experimentally investigated its performance in Orida Bay. The experimentally obtained results indicate that the autonomous navigation of the WDPS boat is possible when the wave height is greater than 5–10 cm.

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