scholarly journals INDIVIDUAL WAVE ANALYSIS OF IRREGULAR WAVE DEFORMATION IN THE NEARSHORE ZONE

1982 ◽  
Vol 1 (18) ◽  
pp. 32 ◽  
Author(s):  
Masaru Mizuguchi
Keyword(s):  
Water Surface ◽  
Surf Zone ◽  
Deterministic Model ◽  
Nearshore Zone ◽  
Irregular Wave ◽  
Wave Deformation ◽  
Individual Wave ◽  
On Line ◽  
Height Change ◽  
Primary Individual

In a field observation, water surface fluctuations were measured at many points on line from the shoreline to just outside the surf zone. The data were analyzed by an individual wave method, where the concept of primary individual wave is introduced in order to investigate irregular wave deformation. Primary individual waves are defined by applying the zero-down crossing method with a suitable band width at the zero level to the high-pass filtered water surface fluctuation. It is shown that a wave thus defined behaves like a regular wave with a fixed period in the nearshore zone. A deterministic model based on wave height change of monochromatic waves on non-uniform beaches is then introduced. The model is found to describe the observed deformation process expressed by the primary individual waves.

scholarly journals A FIELD STUDY OF WAVES IN THE NEARSHORE ZONE

1982 ◽  
Vol 1 (18) ◽  
pp. 3 ◽  
Author(s):  
S. Hotta ◽  
M. Mizuguchi ◽  
M. Isobe
Keyword(s):  
Field Study ◽  
Wave Height ◽  
Surf Zone ◽  
Nearshore Zone ◽  
Camera System ◽  
Joint Distributions ◽  
Initial Analysis ◽  
Sea Bottom ◽  
Initial Results

Initial results are described of precise observations of waves shoaling in the nearshore zone. The key technique of the experiments is a 16 mm memo-motion camera system by which long term measurements of waves can be made simultaneously at many locations. Six or seven pairs of synchronized cameras were mounted on a research pier crossing the surf zone. The cameras were focused on target poles mounted on sleds which were towed about 200 m outside the breaker line, and on a line of poles jetted into the sea bottom across the surf zone. Waves transforming in the nearshore zone were observed from about 400 m offshore to the shoreline. At present only the characteristics of the statistical waves, wave height distributions, wave period distributions, and the joint distributions of wave height and period are described as part of the initial analysis.

scholarly journals MEASUREMENT OF COASTAL CURRENTS

1968 ◽  
Vol 1 (11) ◽  
pp. 27
Author(s):  
J.M. Zeigler ◽  
H.J. Tasha
Keyword(s):  
Carbon Dioxide ◽  
Water Surface ◽  
Surf Zone ◽  
Field Operator ◽  
Compressed Air ◽  
Liquid Carbon ◽  
Wind Drift ◽  
Single Field ◽  
Work Done ◽  
Propellant Rocket

Getting a drift buoy into and over the surf zone in rough weather has always been a problem. A cheap, cold propellant rocket launcher using either compressed air from aqua-lung bottles or liquid carbon dioxide is admirably suited for hurling drift bottles to ranges of over 1,000 feet. This launcher weighs less than one hundred pounds and can be easily transported to places of difficult access such as cliffed or reefy coasts. The float package can be modified to include mid-depth drogues if that is desired. An example of work done by a single field operator illustrates the versatility of this technique . Naval Mark II flares are useful for current tracing because they are easily obtained and can be set in arrays from aircraft. As they burn, however, they change their freeboard and are therefore more subject to wind drift than when they are lower in the water. Mark II flares were calibrated for wind drift with results given. A wind velocity profile between 5/8 inches and 5 inches above the water surface was obtained from floating arrays of flares with the results given.

Irregular Wave Simulation and its Impact on Riser Extreme Response for a Production Semi

2020 ◽  
Author(s):  
Shaosong Zhang ◽  
Yongming Cheng ◽  
Yuanlang Cai ◽  
Ning He ◽  
Xiaolong Yang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wave Spectrum ◽  
Irregular Waves ◽  
Wave Crest ◽  
Multiple Time ◽  
Irregular Wave ◽  
Wave Simulation ◽  
Extreme Response ◽  
Individual Wave ◽  
Wave Properties

Abstract Steel Catenary Risers (SCRs) are widely used in deepwater and ultra-deepwater field developments. The dynamic strength of SCRs is a concern in terms of the global performance. The analysis results are quite scattered in many cases due to the nature of the irregular wave stochastic properties. The widely accepted approach to predict the riser dynamic response in the irregular seas is to run the multiple time domain simulations based on different random seeds. This paper will address the impacts on the predicted riser dynamic response due to the random seeds selection. The discussion is based on the independent engineering verification work for a production Semi project in South China Sea. The site specific irregular waves are usually defined by not only the wave spectrum, but also the properties of individual waves, such as maximum wave height and minimum wave trough, which have big impacts on the riser extreme response. The code recommended approach for irregular wave simulation is based on the linear wave theory, which can ensure the match of the target wave spectrum, for example, Hs, Tp (or Tz), wave peakness for JONSWAP spectrum. But the variation of simulated individual wave properties to the specified value can be significant or there is no specified value to match. The simulated irregular waves based on linear theory is also a distortion to the real wave elevation time trace, such as the asymmetry of the wave crest and trough, especially for the tropical cyclone sea states. Some riser response, such as the compression load at riser touch down zone, can be significantly impacted by the nonlinear nature of the waves and the variation to the target individual wave properties. This paper will discuss the random wave simulation and its impacts on riser dynamic response. A SCR strength design case is presented for illustration in this paper. Key parameters are identified to show the correlation with the SCR dynamic response. The conclusion is finally drawn from the work presented in this paper.

scholarly journals Observation of irregular wave transformation in the surf zone over a gently sloping sandy beach on the French Atlantic coastline

2001 ◽  
Vol 24 (6) ◽  
pp. 545-556 ◽  
Author(s):  
Nadia Sénéchal ◽  
Hélène Dupuis ◽  
Philippe Bonneton ◽  
Hélène Howa ◽  
Rodrigo Pedreros
Keyword(s):  
Sandy Beach ◽  
Surf Zone ◽  
Wave Transformation ◽  
Irregular Wave

Research and Analysis on the Wave Transformation and Irregular Wave Breaking Criterion on the Shore

2016 ◽  
Vol 858 ◽  
pp. 354-358
Author(s):  
Tao You ◽  
Li Ping Zhao ◽  
Zheng Xiao ◽  
Lun Chao Huang ◽  
Xiao Rui Han
Keyword(s):  
Theoretical Model ◽  
Wave Height ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Waves ◽  
Wave Transformation ◽  
Breaking Wave ◽  
Height Distribution ◽  
Flume Experiments ◽  
Irregular Wave

Within the surf zone which is the region extending from the seaward boundary of wave breaking to the limit of wave uprush, breaking waves are the dominant hydrodynamics acting as the key role for sediment transport and beach profile change. Breaking waves exhibit various patterns, principally depending on the incident wave steepness and the beach slope. Based on the equations of conservation of mass, momentum and energy, a theoretical model for wave transformation in and outside the surf zone was obtained, which is used to calculate the wave shoaling, wave set-up and set down and wave height distributions in and outside the surf zone. The analysis and comparison were made about the breaking point location and the wave height variation caused by the wave breaking and the bottom friction, and about the wave breaking criterion under regular and irregular breaking waves. Flume experiments relating to the regular and irregular breaking wave height distribution across the surf zone were conducted to verify the theoretical model. The agreement is good between the theoretical and experimental results.

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