Wave spectrum analysis for extreme wave oscillation inside Paradip port

2019 ◽  
Author(s):  
Gulshan ◽  
Prashant Kumar ◽  
Prashant Patel ◽  
Rupali ◽  
Sukhwinder Kaur
Keyword(s):  
Spectrum Analysis ◽  
Wave Spectrum ◽  
Extreme Wave ◽  
Wave Oscillation

High Speed Rotating Shafts Design Algorithm

1993 ◽  
Author(s):  
Po Kee Wong
Keyword(s):  
Spectrum Analysis ◽  
High Speed ◽  
Wave Spectrum ◽  
Vibrational Modes ◽  
Elastic Rod ◽  
Design Algorithm ◽  
The Public ◽  
Rotating Shafts ◽  
First Time

Abstract This paper reveals an invention for the first time to the public about the fundamental concepts for the design of high speed rotating shafts based on the wave spectrum analysis of the vibrational modes of elastic circular rods and shells that was completed in 1967, even though the Pochhammer-Chree-Love solution of the transversal (n = 1) vibration of a solid elastic rod was originated by Pochhammer in 1876.

Effect of Spectrum Tail Length on Modulational Instability and Freak Wave Occurrence in JONSWAP Sea States

2019 ◽  
Author(s):  
Cagil Kirezci ◽  
Alexander V. Babanin
Keyword(s):  
High Frequency ◽  
Modulational Instability ◽  
Wave Spectrum ◽  
Tail Length ◽  
Shape Parameters ◽  
Extreme Wave ◽  
Freak Wave ◽  
Nonlinear Phase ◽  
Wave Forecasting ◽  
Quantitative Indicators

Abstract In this study, probability of freak wave occurrence due to modulational instability in JONSWAP sea states are investigated. This investigation has been conducted based on the quantitative indicators of instability in wave spectrum, which are two Benjamin-Feir index (BFI) [1,2] with different spectral bandwidth definitions and Π number [3]. Evolution of wave field are simulated using fully nonlinear phase-resolving Chalikov-Sheinin (CS) numerical model [4,5]. Initial sea surface is controlled with JONSWAP shape parameters (α and γ) and random initial phases. Effect of high frequency end of spectrum on modulational instability and freak wave evolution are discussed by considering 4 different tail lengths. According to simulation results, all parameters that are considered here perform as an indicator for the occurrence of extreme events which makes it possible to define a certain interval for indicators, where freak wave occurrence probability is the highest and potentially dangerous, to be possibly used in extreme wave forecasting. Another key finding is that, modulational instability increases when high frequency part of spectrum is present (longer tail) as expected. Nevertheless, after certain nonlinearity, modulational instability is more prone to result in breaking which significantly decreases the probability of occurrence of freak events. Therefore, spectra with shorter tail length result in more dangerous sea states.

Wave Spectrum Analysis of Kerry Deepwater Port Sea in Cameroon

2014 ◽  
Vol 638-640 ◽  
pp. 1280-1284
Author(s):  
Hui Xiao ◽  
Yi Feng Zhang ◽  
Hong Bo Zhao
Keyword(s):  
Fourier Transform ◽  
Spectrum Analysis ◽  
Wave Spectrum ◽  
Transform Method ◽  
Long Period ◽  
Fast Fourier Transform Method ◽  
Spectrum Characteristics ◽  
One Year ◽  
Sea Area ◽  
Period Wave

According to the measured wave data for one year in Kerry deepwater port sea area, Cameroon, the wave spectrum characteristics calculate using fast Fourier transform method; the result shows that the bimodal spectrum is given priority to this sea area, and the big wave appears in summer and autumn, the long period wave influence is opposite bigger that should be pay attention.

Local Energy Spectra in the Vicinity of an Extreme Wave Event

2003 ◽  
Author(s):  
Richard Gibson ◽  
Chris Swan
Keyword(s):  
Wave Spectrum ◽  
Wave Model ◽  
Extreme Wave ◽  
Time Frequency ◽  
Recent Advances ◽  
Rapid Changes ◽  
Wave Event ◽  
Local Wave ◽  
Water Particle Kinematics ◽  
Extreme Wave Event

Previous work by Baldock, Swan and Taylor [1], Johannessen and Swan [2,3], and Bateman, Swan and Taylor [4,5] has demonstrated that in the vicinity of an extreme wave event there are significant and rapid changes in the local wave spectrum. The present paper combines two recent advances. The first is a new fully nonlinear directional wave model, the application of which is particularly suited to the description of extreme waves arising in realistic sea states. The second involves recent advances in time-frequency analysis techniques. Unlike traditional spectral analysis, based upon the Fourier transform, these allow local and rapid changes in a wave spectrum to be clearly identified. By combining these methods the proposed paper will first highlight the occurrence of these changes in realistic seas and will subsequently demonstrate their significance both in terms of estimating crest height elevations and in predicting the associated water particle kinematics.

Linearization of the Wave Spectrum: A Comparison of Methods

2020 ◽  
Author(s):  
Dylan Barratt ◽  
Harry B. Bingham ◽  
Paul H. Taylor ◽  
Ton S. van den Bremer ◽  
Thomas A. A. Adcock
Keyword(s):  
Fourier Transform ◽  
Phase Separation ◽  
Wave Field ◽  
Wave Spectrum ◽  
Three Dimensional ◽  
Extreme Wave ◽  
Offshore Engineering ◽  
Wave Event ◽  
The Fourier Transform ◽  
Spurious Modes

Abstract The relative contributions of free waves and bound waves to the formation of an extreme wave event remains a topic of interest in offshore engineering. A variety of methods have been proposed for identifying and removing the bound wave components. The method of “phase separation” or “phase manipulation” repeats simulations/experiments of a wave field with an offset in the initial phase of the wave components and relies upon summation of the resulting wave fields to isolate the bound harmonics, following from a Stokes expansion in steepness; the method has proven effective in isolating bound harmonics but requires that all cases be repeated. Alternatively, the bound harmonics can be removed using a three-dimensional fast Fourier transform (3D-FFT) of the wave field. However, the Fourier transform requires periodicity in the signal and assumes homogeneity in space and stationarity in time, producing spurious modes otherwise. We compare the phase separation and 3D-FFT approaches for a steep, focusing wave group in deep water using the numerical simulation tool, OceanWave3D, and discuss the effectiveness of both methods.

scholarly journals 3-D HOS simulations of extreme waves in open seas

2007 ◽  
Vol 7 (1) ◽  
pp. 109-122 ◽  
Author(s):  
G. Ducrozet ◽  
F. Bonnefoy ◽  
D. Le Touzé ◽  
P. Ferrant
Keyword(s):  
Wave Spectrum ◽  
Original Study ◽  
Test Cases ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Freak Waves ◽  
Freak Wave ◽  
Directional Spectrum ◽  
Long Time ◽  
Directional Wave

Abstract. In the present paper we propose a method for studying extreme-wave appearance based on the Higher-Order Spectral (HOS) technique proposed by West et al. (1987) and Dommermuth and Yue (1987). The enhanced HOS model we use is presented and validated on test cases. Investigations of freak-wave events appearing within long-time evolutions of 2-D and 3-D wavefields in open seas are then realized, and the results are discussed. Such events are obtained in our periodic-domain HOS model by using different kinds of configurations: either i) we impose an initial 3-D directional spectrum with the phases adjusted so as to form a focused forced event after a while, or ii) we let 2-D and 3-D wavefields defined by a directional wave spectrum evolve up to the natural appearance of freak waves. Finally, we investigate the influence of directionality on extreme wave events with an original study of the 3-D shape of the detected freak waves.

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