Instability of nonlinear standing waves in front of a vertical wall

Romańczyk, W.

doi:10.1016/j.jfluidstructs.2006.10.013

Cited by 5 publications

(2 citation statements)

References 35 publications

(33 reference statements)

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“…Similarly, for long waves compared to the water depth, cnoidal wave theory applies [45]. Romanczyk [46] describes that steep standing waves become remarkably unstable. The majority of the mentioned studies refer to regular standing waves.…”

Section: Literaturementioning

confidence: 99%

Experimental Observations on Impact Velocity and Entrapped Air for Standing Wave Impacts on Vertical Hydraulic Structures with Overhangs

Sousa

Hofland

2020

JMSE

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This study focusses on increasing the understanding on vertical hydraulic structures with relatively short overhangs subjected to standing wave impacts. To this end, the impact velocity and the entrapped air are studied in detail, given their influence on the impulsive loading characteristics and consequently on the structural dynamic response. This study is based on regular wave laboratory experimental data obtained for relatively short overhangs with respect to the wave length and with respect to the overhang height. The laboratory tests illustrate the complex wave hydrodynamics before the wave impacts, influenced by the incident wave conditions and structural characteristics. Regarding the impact velocity, the experimental measurements with a wall wave gauge in the tests without overhangs show that the maximum upward velocities deviate from linear wave theory between +5.5% and +13.0%, while the zero-crossing upward velocities deviate from linear wave theory between +1.9% and +7.0%. The zero-crossing upward velocities estimated from third order wave theory deviate from the linear wave theory between +1.8% and +4.7%. In the tests with overhangs, the maximum upward velocity below the overhang estimated by camera recording measurements deviates from linear wave theory between −11.8% and +13.4%. It was also found that when considering the experimental impact velocity from camera recordings in the tests with overhangs, the mean effective bounce-back factor β deviates relatively little from when linear wave theory is used (≈1%), while the uncertainty described by the standard deviation increases significantly (≈35%). Regarding the entrapped air, it is shown that the interaction between incident wave parameters and structural configurations leads to a large variation in the entrapped air area, up to a factor of 5.7 for shorter overhangs and a factor of 9.5 for longer overhangs. This variability in entrapped air characteristics leads to significant effects on the loading on the structure, as observed by the variability on pressure measurements. The experimental results showed increasing impact durations and increasing effective bounce-back factor β in the tests with increasing entrapped air dimensions. This study highlights the importance of the details of the impact velocity and entrapped air for load estimations during the design of vertical hydraulic structures exposed to standing wave impacts. This is particularly important for thin structures such as steel gates which are susceptible to a dynamic behaviour under such impulsive loads.

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Section: Literaturementioning

confidence: 99%

Experimental Observations on Impact Velocity and Entrapped Air for Standing Wave Impacts on Vertical Hydraulic Structures with Overhangs

Sousa

Hofland

2020

JMSE

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“…Higher order effects are more prominent when 'double humps' are observed at the water level or in the wave force for an increasing wave steepness (Goda, 1966). Recent studies show the 'double humps' for wave pressures (Romanczyk, 2007) and water level elevations (Chen Yang-Yih, 2009) 1.2 Goda, Spectral LWT, NewWave and Quadratic LWT A frequently applied formula for engineering purposes is the formula of Goda (1974Goda ( , 2010. The Goda formula is derived for the design of caisson breakwaters and considers failure modes like sliding, overturning, and failure of the foundation (Goda, 2010).…”

Section: Introduction 1backgroundmentioning

confidence: 98%

Evaluation and validation of the spectral linear wave theory and ‘traditional’ formulae for pulsating wave loads for unimodal and bimodal seas

Tuin,

Voortman,

Hofland

et al. 2022

Journal of Coastal and Hydraulic Structures

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For the design of vertical hydraulic structures pulsating wave forces need to be calculated. The total wave force is a result of every wave component (long waves and short waves) within a wave field. The common formulae are derived for regular or unimodal narrow sea states and use one characteristic wave height and period. Broad-banded spectra like bimodal sea states are present at many locations. Moreover, new hydraulic structures like Panamax or post-Panamax locks do have a large vertical surface exposed to pulsating wave loads. Swell components within the wave spectrum are disproportionally contributing to the total wave force compared to short waves. This depth effect for broad-banded or bimodal wave spectra is not considered by the traditional wave formulae which could result in significant underestimations of wave forces on hydraulic structures. This paper aims to determine the wave loads of irregular non-breaking wave fields under any wave spectrum: narrow banded, broad-banded, or bimodal. Spectral linear wave theory (LWT) is used to transform any wave spectrum to a wave force spectrum. The wave force or wave pressure at any level can directly be evaluated from the wave force spectrum or wave pressure spectrum for any shape of the wave spectrum considered within this research. Spectral LWT is compared to the outcome of wave flume experiments with bimodal seas and other wave force formulae, like the Goda formula and quasi-regular LWT and the NewWave theory. This paper gives a description and evaluation of the spectral LWT applied for bimodal wave spectra and a comparison of the accuracy and validity of other wave force formulae. The peak forces and peak pressures distribution obtained by spectral wave theory compare well to the measurements. It appears that the use of a spectral LWT to obtain characteristic extreme forces improves the accuracy of the extreme load more than the use of a second order wave model with a quasi-regular assumption (i.e. where the spectral shape is not considered). For the typical conditions that occur at hydraulic structures (horizontal bed, intermediate to deep water, non-breaking, and uni- and bimodal seas) the often-used Goda formula can both under of overestimate the peak loads. Goda is well applicable for conditions with (breaking) waves narrow wave spectra and values of kph <0.5.

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Data analysis on safety factors of physical modeling structures based on the computation of incident impact

Luo

Yang

et al. 2017

Cluster Comput

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Instability of nonlinear standing waves in front of a vertical wall

Cited by 5 publications

References 35 publications

Experimental Observations on Impact Velocity and Entrapped Air for Standing Wave Impacts on Vertical Hydraulic Structures with Overhangs

Experimental Observations on Impact Velocity and Entrapped Air for Standing Wave Impacts on Vertical Hydraulic Structures with Overhangs

Evaluation and validation of the spectral linear wave theory and ‘traditional’ formulae for pulsating wave loads for unimodal and bimodal seas

Data analysis on safety factors of physical modeling structures based on the computation of incident impact

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