scholarly journals DIRECTIONAL WAVE SPECTRA AND WAVE KINEMATICS IN HURRICANES CARMEN AND ELOISE

1980 ◽  
Vol 1 (17) ◽  
pp. 34
Author(s):  
G.Z. Forristall ◽  
E.G. Ward ◽  
V.J. Cardone
Keyword(s):  
Wave Height ◽  
Local Equilibrium ◽  
Wave Theory ◽  
Electromagnetic Current ◽  
Linear Wave ◽  
Directional Spectrum ◽  
Wave Kinematics ◽  
Storm Waves ◽  
Velocity Probability ◽  
Realistic Description

A realistic description of the kinematics of hurricane waves requires that the directional spectrum of the sea be known. Models for hindcasting the directional spectrum have existed for some time, but there has been a dearth of data available for checking the directional characteristics of the hindcasts. Hurricane Carmen in 1974 and hurricane Eloise in 1975 passed reasonably close to platforms in the Gulf of Mexico which were instrumented with wave staffs and electromagnetic current meters. The maximum recorded significant wave height was 29 feet. The simultaneous measurements of wave height and water particle velocity permitted estimates of the directional spectra to be made. The estimated directional spectra are complicated and often bimodal in frequency and direction. Swell from the center of the storm can propagate in directions over 90 degrees away from the direction of the shorter waves which are in local equilibrium with the wind. The hindcast model reproduces these directional features remarkably well. The measurements of wave kinematics also permitted tests of the accuracy of wave theories in high and confused storm waves. All of the unidirectional theories tested showed a bias toward overpredicting the velocity under the highest waves. However, the kinetic energy in the velocity components and the velocity probability distribution could be found to within a ten percent scatter using directional spectral concepts and linear wave theory.

scholarly journals EFFECT OF WAVE-CURRENT INTERACTION ON THE WAVE PARAMETER

1982 ◽  
Vol 1 (18) ◽  
pp. 28
Author(s):  
Yu-Cheng Li ◽  
John B. Herbich
Keyword(s):  
Wave Height ◽  
Wave Length ◽  
Wave Theory ◽  
Length Change ◽  
Numerical Calculations ◽  
Wave Parameter ◽  
Linear Wave ◽  
Linear Wave Theory ◽  
Wide Range ◽  
Non Linear

The interaction of a gravity wave with a steady uniform current is described in this paper. Numerical calculations of the wave length change by different non-linear wave theories show that errors in the results computed by the linear wave theory are less than 10 percent within the range of 0.15 < d/Ls s 0.40, 0.01 < Hs/Ls < 0.07 and -0.15 < U/Cs i 0.30. Numerical calculations of wave height change employing different wave theories show that errors in the results obtained by the linear wave theory in comparison with the non-linear theories are greater when the opposing relative current and wave steepness become larger. However, within range of the following currents such errors will not be significant. These results were verified by model tests. Nomograms for the modification of wave length and wave height by the linear wave theory and Stokes1 third order theory are presented for a wide range of d/Ls, Hs/Ls and U/C. These nomograms provide the design engineer with a practical guide for estimating wave lengths and heights affected by currents.

scholarly journals THE MEASURED PROPERTIES OF IRREGULAR WAVE BREAKING AND WAVE HEIGHT CHANGE AFTER BREAKING ON THE SLOPE

1988 ◽  
Vol 1 (21) ◽  
pp. 29 ◽  
Author(s):  
Akira Seyama ◽  
Akira Kimura
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Wave Theory ◽  
Irregular Waves ◽  
Linear Wave ◽  
Periodic Waves ◽  
Zero Crossing ◽  
Irregular Wave ◽  
Height Change ◽  
Cross Waves

Wave height change of the zero-down-cross waves on uniform slopes were examined experimentally. The properties of shoaling, breaking and decay after breaking for a total of about 4,000 irregular waves of the Pierson-Moskowitz type on 4 different slopes (1/10, 1/20, 1/30 and 1/50) were investigated. The shoaling property of the zero-down-cross waves can be approximated by the linear wave theory. However, the properties of breaking and decay after breaking differ considerably from those for periodic waves. The wave height water depth ratio (H/d) at the breaking point for the zero-down-cross waves is about 30% smaller than that for periodic waves on average despite the slopes. Wave height decay after breaking also differs from that for periodic waves and can be classified into three regions, i.e. shoaling, plunging and bore regions. Experimental equations for the breaking condition and wave height change after breaking are proposed in the study. A new definition of water depth for the zero-crossing wave analysis which can reduce the fluctuation in the plotted data is also proposed.

Investigation of Shallow Water Kinematics and Local Loading Effects on Reliability of Minimum Structures

2001 ◽  
Vol 124 (1) ◽  
pp. 41-47
Author(s):  
Suhartodjo Tuty ◽  
Mark J. Cassidy ◽  
Beverley F. Ronalds
Keyword(s):  
Shallow Water ◽  
Stream Function ◽  
Function Theory ◽  
Strong Relationship ◽  
Wave Theory ◽  
Wave Crest ◽  
Linear Wave ◽  
North West ◽  
Wave Kinematics ◽  
The North

In shallow water, and specifically for minimum structures, the critical wave height exponent α has been shown to vary significantly with structural configuration. Because of the strong relationship to the wave kinematics, α is also sensitive to the wave theory chosen. The North West Shelf offshore Australia has numerous minimum structures located in relatively shallow water, which requires non-linear wave theory. In the near-breaking condition, estimation of the wave crest kinematics is difficult, with Stream Function theory being the most widely used. However, various other wave theories and nonlinear numerical techniques have been developed to predict wave kinematics for shallow water conditions. The following wave theories are compared: regular Stream Function theory, Cnoidal wave theory, Stokes’ theory, NewWave theory, and a second-order correction to NewWave theory. Kinematics, loads and α results are presented for a cylinder in three different water depths.

Effect of Applying 2nd Order Wave Theory on Pipeline Dynamic Response

2010 ◽  
Author(s):  
Hammam Zeitoun ◽  
Knut To̸rnes ◽  
Stuart Oldfield ◽  
Gary Cumming ◽  
Andrew Pearce ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wave Theory ◽  
Higher Order ◽  
Cost Driver ◽  
Design Solution ◽  
Linear Wave ◽  
Finite Elements Analysis ◽  
Linear Wave Theory ◽  
Wave Kinematics ◽  
Subsea Pipelines

Ensuring subsea pipelines on-bottom stability by determining the stabilisation requirements which will limit pipelines movement under extreme waves and currents is an essential aspect of subsea pipelines design. These requirements can be a major project cost driver in some locations around the world, where the designer is faced with severe metocean conditions. This is particularly the case when the selected design solution is associated with costly stabilisation requirements such as trenching, anchoring [14], rock dumping, or mattressing. An appreciation of the pipeline structural response, when exposed to waves and steady currents kinematics is fundamental to optimise the stabilisation solution. An advanced approach used to optimise stabilisation requirements is to use transient dynamic finite element analysis. The analysis is used to simulate the dynamic response of subsea pipelines exposed to near-seabed kinematics, due to a combination of steady currents and waves. Wave kinematics at the seabed are therefore an essential input to the analysis and will significantly affect both the hydrodynamic loads on the pipeline and the pipeline response. The typical method for generating the wave kinematics in a dynamic analysis has been based on calculating the near-bed velocities corresponding to a randomly generated seastate, using linear wave theory. It has been acknowledged that this calculation is likely to produce a conservative estimate of the positive wave velocities. An improved prediction of seabed kinematics can be achieved by using higher order wave theories. Application of higher order wave theories, results in changing the velocity magnitude under wave crests and troughs. This change in kinematics may result in a change of pipeline response. This paper investigates the effect of using 2nd order wave theory for predicting the kinematics on the pipeline dynamic response. Dynamic finite elements analysis is used for determining the pipeline response and to compare the pipeline response when using 2nd order wave theory and linear wave theory. The work presented in this paper was commissioned by Woodside and performed by J P Kenny Pty Ltd.

scholarly journals Wave Energy Potential and Simulation on the Andaman Sea Coast of Thailand

2020 ◽  
Vol 12 (9) ◽  
pp. 3657 ◽  
Author(s):  
Chutipat Foyhirun ◽  
Duangrudee Kositgittiwong ◽  
Chaiwat Ekkawatpanit
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Measurement Data ◽  
Wave Theory ◽  
Andaman Sea ◽  
Linear Wave ◽  
Energy Potential ◽  
Significant Wave ◽  
Linear Wave Theory ◽  
Swan Model

Ocean wave energy is an interesting renewable energy because it will never run out and can be available all the time. If the wave energy is to be used, then the feasibility study of localized wave potential has to be studied. This goal is to study the potential of waves in the Andaman Sea. The Simulating WAves Nearshore (SWAN) model was used to calculate the significant wave heights, which were validated with the measurement data of the Jason-2 satellite. The coastal area of Phuket and Phang Nga provinces are suitable locations for studying wave energy converters because they have high significant wave height. Moreover, this study used computational fluid dynamics (CFD) for the simulation of wave behavior in accordance with wave parameters from the SWAN model. The wave height simulated from CFD was validated with linear wave theory. The results found that it was in good agreement with linear wave theory. It can be applied for a simulation of the wave energy converter.

scholarly journals WAVE HEIGHT DECAY MODEL WITHIN A SURF ZONE

1986 ◽  
Vol 1 (20) ◽  
pp. 52
Author(s):  
Shigeki Sakai ◽  
Kouetsu Hiyamizu ◽  
Hiroshi Saeki
Keyword(s):  
Energy Dissipation ◽  
Wave Height ◽  
Surf Zone ◽  
Wave Theory ◽  
Momentum Balance ◽  
Breaking Wave ◽  
Good Prediction ◽  
Linear Wave ◽  
Energy And Momentum ◽  
Spilling Breaker

A model for wave height decay of a spilling breaker is proposed. The energy dissipation of a breaking wave is approximated by that of a propagating bore. In order to explain the gentle decay of spilling breaker at the initial stage, a development of a foam region, which indicates the amount of foam on the wave profile and determines the rate of energy dissipation, is considered. In addition to this formulation, the energy and momentum balance equations are described by a linear wave theory in shallow water and are simultaneously solved. Comparisons with experimental results show that the model gives a good prediction in both inner and outer regions, and that two coefficients in the present model are related to the deep water wave steepness and the slope of beaches.

A Second Order Lagrangian Model for Irregular Ocean Waves

2005 ◽  
Vol 128 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Sébastien Fouques ◽  
Harald E. Krogstad ◽  
Dag Myrhaug
Keyword(s):  
Specular Reflection ◽  
Fluid Velocity ◽  
Equations Of Motion ◽  
Wave Theory ◽  
Ocean Waves ◽  
Second Order ◽  
Lagrangian Model ◽  
Lagrangian Description ◽  
Linear Wave ◽  
Irregular Solution

Synthetic aperture radar (SAR) imaging of ocean waves involves both the geometry and the kinematics of the sea surface. However, the traditional linear wave theory fails to describe steep waves, which are likely to bring about specular reflection of the radar beam, and it may overestimate the surface fluid velocity that causes the so-called velocity bunching effect. Recently, the interest for a Lagrangian description of ocean gravity waves has increased. Such an approach considers the motion of individual labeled fluid particles and the free surface elevation is derived from the surface particles positions. The first order regular solution to the Lagrangian equations of motion for an inviscid and incompressible fluid is the so-called Gerstner wave. It shows realistic features such as sharper crests and broader troughs as the wave steepness increases. This paper proposes a second order irregular solution to these equations. The general features of the first and second order waves are described, and some statistical properties of various surface parameters such as the orbital velocity, slope, and mean curvature are studied.

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