Kinematics and dynamics of green water on a fixed platform in a large wave basin in focusing wave and random wave conditions

Chuang, Wei‐Liang; Chang, Kuang‐An; Mercier, Richard

doi:10.1007/s00348-018-2554-8

Cited by 26 publications

(13 citation statements)

References 33 publications

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“…The BIV technique is capable of measuring velocities in the aerated region of a gas‐liquid flow, such as the breaking waves in the present study. More details about the principles and validation of the BIV technique can be found in Ryu et al (, ), Chang et al (), Chuang et al (, ), Lim et al (), and Na et al ().…”

Section: Turbulence Statisticsmentioning

confidence: 99%

Laboratory Observation of Turbulence and Wave Shear Stresses Under Large Scale Breaking Waves Over a Mild Slope

Hsu

Huang

et al. 2019

JGR Oceans

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Laboratory measurements of turbulent flow and shear stresses in a surf zone under monochromatic breaking waves in a large‐scale wave flume are presented. Waves with various surf similarity parameters were generated to break at nearly identical water depths over a 1/100 mild slope. Free surface elevations were measured along the plane beach. Velocities in a water column located at the breaking region were measured by acoustic Doppler velocimeters. Results from wave shoaling coefficient, breaking index, and images are inconsistent with the breaker type categorizations from the surf similarity parameter. This suggests that a modification of the surf similarity parameter for very mild slopes may be necessary. For the plunging breakers, the ensemble‐averaged results indicate that intense turbulence kinetic energy was initially generated by large eddies at the surface then transported to the bottom frequently. The instantaneous results demonstrate that the intermittency of turbulence kinetic energy near the bed was caused by large eddies generated by wave overturning and relatively smaller obliquely descending eddies. Moreover, the magnitude of the wave shear stress (WSS) is one order of magnitude larger than that of the turbulent shear stress, indicating that the effects of the bottom slope, wave breaking, and bed friction are significant in the surf zone. The sign of the time‐averaged WSS switched between positive and negative, depending on the occurrences of phase lag and phase lead of the vertical coherent velocity. It suggests that a change may be required in Zou et al.'s (2006, https://doi.org/10.1029/2005JC003300) theory on the formulation of wave‐breaking induced WSS.

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Section: Turbulence Statisticsmentioning

confidence: 99%

Laboratory Observation of Turbulence and Wave Shear Stresses Under Large Scale Breaking Waves Over a Mild Slope

Hsu

Huang

et al. 2019

JGR Oceans

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“…Substantial research works investigated the extreme wave impact on platform structures with the emphasis on different aspects such as the wave slamming loads [19,20,51,50,73] and the wave overtopping [21,56,13,11]. An important phenomenon during the wave structure interaction process is the negative pressure (or suction effect) that was discussed by [19] and more recently by [51] and [50].…”

Section: Introductionmentioning

confidence: 99%

The suction effect during freak wave slamming on a fixed platform deck: Smoothed particle hydrodynamics simulation and experimental study

et al. 2019

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During the process of wave slamming on a structure with sharp corners, the wave receding after wave impingement can induce strong negative pressure (relative to the atmospheric pressure) at the bottom of the structure, which is called the suction effect. From the practical point of view, the suction force induced by the negative pressure, coinciding with the gravity force, pulls the structure down and hence increases the risk of structural damage. In this work, the smoothed particle hydrodynamics (SPH) method, more specifically the δ + SPH model, is adopted to simulate the freak wave slamming on a fixed platform with the consideration of the suction effect, i.e. negative pressure, which is a challenging issue because it can cause the so-called tensile instability (TI) in SPH simulations. Key to overcome the numerical issue is to use a numerical technique named tensile instability control (TIC). Comparative studies using SPH models with and without TIC will show the importance of this technique in capturing the negative pressure. It is also found that using a two-phase simulation that takes the air phase into account is essential for an SPH model to accurately predict the impact pressure during the initial slamming stage. The freak wave impacts with different water depths are studied. All the multiphase SPH results are validated by our experimental data. The wave kinematics/dynamics and wave impact features in the wave-structure interacting process are discussed and the mechanism of the suction effect characterized by negative pressure is carefully analyzed.

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“…Finally, as described by [2,8], the flow patterns over the deck will depend on the features of the incident waves, which can be unbroken (e.g., [9][10][11]17]) or broken (e.g., [5][6][7][8]73,74]). In the latter, if unsteady and broken flow can be observed on the deck (see the snapshots in Figure 16 and in [4]), then the application of numerical models, rather than analytical models, could be used for detailed research.…”

Section: Some Challenges In Assessing Green Water Propagationmentioning

confidence: 99%

“…In ocean engineering research, experimental observations have suggested various patterns used to characterize different types of green water. Broken flow features are often seen, if they are generated by breaking waves [5][6][7][8], or air cavity formation at the start of the deck, if the incident waves are unbroken or partially broken [9][10][11][12][13][14]. In 2007, a classification of different types of green water was suggested by [9], who described the different events found in regular wave trains: The dam-break (DB), the plunging-dambreak (PDB), and the hammer-fist (HF) types.…”

Section: Introductionmentioning

confidence: 99%

On the Evolution of Different Types of Green Water Events

Hernández-Fontes

Hernández

Mendoza

et al. 2021

Water

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Green water events may present different features in the initial stage of interaction with the deck of a structure. It is therefore important to investigate the evolution of different types of green water, since not all the events interact with the deck at the same time. In this paper, the evolution of three types of green water events (dam-break, plunging-dam-break, and hammer-fist) are studied. The water surface elevations and volumes over the deck in consecutive green water events, generated by incident [wave trains in a wave flume, were analyzed using image-based methods. The results show multiple-valued water surface elevations in the early stage of plunging-dam-break and hammer-fist type events. Detailed experimental measurements of this stage are shown for the first time. The effect of wave steepness on the duration of the events, maximum freeboard exceedance, and volumes were also investigated. Although the hammer-fist type showed high freeboard exceedances, the plunging-dam-break type presented the largest volumes over the deck. Some challenges for further assessments of green water propagation are reported.

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Kinematics and dynamics of green water on a fixed platform in a large wave basin in focusing wave and random wave conditions

Cited by 26 publications

References 33 publications

Laboratory Observation of Turbulence and Wave Shear Stresses Under Large Scale Breaking Waves Over a Mild Slope

Laboratory Observation of Turbulence and Wave Shear Stresses Under Large Scale Breaking Waves Over a Mild Slope

The suction effect during freak wave slamming on a fixed platform deck: Smoothed particle hydrodynamics simulation and experimental study

On the Evolution of Different Types of Green Water Events

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