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17 pages, 4679 KiB

Open AccessArticle

Predictions of Wave Overtopping Using Deep Learning Neural Networks

by Yu-Ting Tsai and Ching-Piao Tsai

J. Mar. Sci. Eng. 2023, 11(10), 1925; https://doi.org/10.3390/jmse11101925 - 05 Oct 2023

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Deep learning techniques have revolutionized the field of artificial intelligence by enabling accurate predictions of complex natural scenarios. This paper proposes a novel convolutional neural network (CNN) model that involves deep learning technologies, such as the bottleneck residual block, layer normalization, and dropout [...] Read more.

Deep learning techniques have revolutionized the field of artificial intelligence by enabling accurate predictions of complex natural scenarios. This paper proposes a novel convolutional neural network (CNN) model that involves deep learning technologies, such as the bottleneck residual block, layer normalization, and dropout layer, to predict wave overtopping at coastal structures under a wide range of conditions. To optimize the performance of the CNN model, the hyperparameter tuning process via Bayesian optimization is used. The results of validation demonstrate that the proposed CNN model is highly accurate in estimating wave overtopping discharge from hydraulic and structural parameters. The testing accuracy of the overtopping predictions using a prototype dataset shows that the proposed CNN model outperforms those existing machine learning models. An example application of the CNN model is presented for predicting prototype overtopping considering various crest freeboards of coastal structures. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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24 pages, 9003 KiB

Open AccessArticle

Hydraulic Response and Overtopping Performance of Single-Layer Double Cube Unit Armored Mound Breakwater

by Iman Safari, Dominique Mouazé, Soroush Aliasgary, Guillaume Carpentier and François Ropert

J. Mar. Sci. Eng. 2023, 11(7), 1382; https://doi.org/10.3390/jmse11071382 - 06 Jul 2023

Viewed by 847

Abstract

A newly developed friction-interlocking armor unit called the ‘Double cube’ (DC) was designed to improve the performance of a concrete armor unit used in river/marine structures against currents/waves actions. The DC unit is an octagonal-shaped block made up of two parts: an upper [...] Read more.

A newly developed friction-interlocking armor unit called the ‘Double cube’ (DC) was designed to improve the performance of a concrete armor unit used in river/marine structures against currents/waves actions. The DC unit is an octagonal-shaped block made up of two parts: an upper cube set on a lower base that is either square or octagonal in shape. The innovative design aims to provide good performance in terms of stability, to allow for high tolerance placement with various contact points, and to allow for ease of placement. The DC’s shape and placement enhance the unit’s stability by bringing the center of gravity closer to the underlayer and by providing a large contact surface with the surrounding blocks that reduces the chance of extraction and limits movements (rocking, lifting) via the “keystone” effect. The characteristics of this new unit provide a relatively high hydraulic stability number for the armor layer (N_S = 2.9), a favorable hydraulic performance due to energy dissipation from turbulence and aeration, as well as a high roughness coefficient (γ_f ≈ 0.46), helping to reduce overtopping. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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19 pages, 2814 KiB

Open AccessArticle

Wave Transmission over Rubble-Mound Submerged Breakwaters

by Elpidoforos Repousis, Ioannis Roupas and Constantine Memos

J. Mar. Sci. Eng. 2023, 11(7), 1346; https://doi.org/10.3390/jmse11071346 - 01 Jul 2023

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Abstract

This study focuses on the prediction of technical efficiency of narrow-crested submerged permeable rubble-mound breakwaters, in terms of wave attenuation. A number of existing formulae for estimating wave transmission coefficient for submerged breakwaters can be found in the literature, whereas in this work [...] Read more.

This study focuses on the prediction of technical efficiency of narrow-crested submerged permeable rubble-mound breakwaters, in terms of wave attenuation. A number of existing formulae for estimating wave transmission coefficient for submerged breakwaters can be found in the literature, whereas in this work further improvement for that estimation has been achieved mainly through physical modelling. A series of 2D experiments under scale were conducted for regular and random waves providing data on wave transmission coefficient and respective wave breaking characteristics. A Boussinesq-type wave model capable of simulating wave propagation for regular waves over porous submerged breakwaters was also used in order to provide additional wave transmission information. Data analysis showed that wave breaking mechanism significantly affects wave energy dissipation and, therefore, wave breaking occurrence and type can be directly linked to wave transmission coefficient for a given structure’s geometry and sea state. The result of this work is the proposal of a set of simple semi-empirical equations for predicting wave transmission coefficient over small profile porous submerged breakwaters in relevance to the parameterization of the expected dominant wave breaking mechanism. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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15 pages, 6531 KiB

Open AccessArticle

Experimental Investigation of Wave Loads on U-OWC Breakwater

by Alessandra Romolo, Bruna Timpano, Valentina Laface, Vincenzo Fiamma and Felice Arena

J. Mar. Sci. Eng. 2023, 11(1), 19; https://doi.org/10.3390/jmse11010019 - 23 Dec 2022

Cited by 1 | Viewed by 1244

Abstract

A small-scale field experiment was conducted on a U-OWC incorporated into a caisson breakwater at the NOEL laboratory of Reggio Calabria (Italy). The U-Oscillating Water Column (U-OWC) or REWEC (REsonant Wave Energy Converter) is a device belonging to the family of OWCs. Such [...] Read more.

A small-scale field experiment was conducted on a U-OWC incorporated into a caisson breakwater at the NOEL laboratory of Reggio Calabria (Italy). The U-Oscillating Water Column (U-OWC) or REWEC (REsonant Wave Energy Converter) is a device belonging to the family of OWCs. Such a device is very innovative, being able to absorb a very high percentage of incoming sea waves energy and to produce electrical power via proper PTO. The focus of the paper has been the analysis of the impact wave loads acting on the modified U-OWC structure during extreme wave events. A total of 250 records of pure wind waves were analyzed to verify the behaviors of wave loads acting on a U-OWC breakwater during operating conditions. The occurrence of both “quasi-standing wave” loads due to non-breaking waves and “impulsive wave loads”, exerted by a wave breaking against the U-OWC model, were observed. Then, Goda’s model was applied to predict the wave pressure distribution on the external wall of the U-OWC pneumatic chamber, and the theoretical results were compared to those obtained via small-scale field experiment. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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19 pages, 6480 KiB

Open AccessArticle

Application of SWASH to Compute Wave Overtopping in Ericeira Harbour for Operational Purposes

by Anika Manz, Ana Catarina Zózimo and Juan L. Garzon

J. Mar. Sci. Eng. 2022, 10(12), 1881; https://doi.org/10.3390/jmse10121881 - 03 Dec 2022

Cited by 1 | Viewed by 1329

Abstract

This work aimed at testing the capability of the numerical model SWASH to be implemented in the prototype of the overtopping and flooding forecast system HIDRALERTA for Ericeira harbour. In contrast to the neural network NN_OVERTOPPING2, which is currently implemented in HIDRALERTA, SWASH [...] Read more.

This work aimed at testing the capability of the numerical model SWASH to be implemented in the prototype of the overtopping and flooding forecast system HIDRALERTA for Ericeira harbour. In contrast to the neural network NN_OVERTOPPING2, which is currently implemented in HIDRALERTA, SWASH is able to estimate the flood extension and wave propagation along the domain, which makes it a possible improvement to NN_OVERTOPPING2. The one-dimensional version of the SWASH model was implemented to simulate overtopping at two different profiles (antifer and tetrapods) and calibrated for three storms in 2019 by comparing the simulated overtopping discharge to NN_OVERTOPPING2 results. For the calibration, the Manning coefficient was used to represent the friction of the armour layer. Then, for operational purposes, four expressions to calculate the Manning coefficient were developed based on: the relative crest freeboard, the wave steepness, the incident wave angle and the type of armour layer. The expressions showed small errors between the calculated and calibrated Manning coefficients and highlighted the importance of the incident wave angle to obtain an accurate calibration. Despite an underestimation of the overtopping discharge in some cases, the SWASH model was found to provide overall good results when applied with calculated Manning coefficients and suitable to be implemented in HIDRALERTA. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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14 pages, 12651 KiB

Open AccessArticle

Coastal Defences on Low-Lying Reef Flats: A Laboratory Study of Seawall Shape and Position

by Goélanne Rossignol and Damien Sous

J. Mar. Sci. Eng. 2022, 10(11), 1652; https://doi.org/10.3390/jmse10111652 - 04 Nov 2022

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Abstract

The present study reports on a series of laboratory experiments aiming to understand and to optimize the deployment of seawall defences over low-lying coral reef flats. The study is performed in a purely cross-shore configuration, with varying wave forcing, water depth, and seawall [...] Read more.

The present study reports on a series of laboratory experiments aiming to understand and to optimize the deployment of seawall defences over low-lying coral reef flats. The study is performed in a purely cross-shore configuration, with varying wave forcing, water depth, and seawall shapes and positions along the reef flat. The observations reveal the individual and combined effects of the external parameters. A higher seawall efficiency is reached for low waves, shallow water depth, seaward position, and a stepped seawall shape. A dimensionless formulation is proposed to predict the short wave transmission coefficient dependency on the seawall freeboard, incoming wave height, berm width, and seawall shape. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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31 pages, 12201 KiB

Open AccessArticle

Wave Height Reduction Inside Pohang New Port, Korea, Due to the Construction of a Detached Breakwater

by Kyong Ho Ryu, Weon Mu Jeong, Jung-Eun Oh, Won-Dae Baek and Yeon S. Chang

J. Mar. Sci. Eng. 2022, 10(10), 1537; https://doi.org/10.3390/jmse10101537 - 19 Oct 2022

Cited by 2 | Viewed by 1613

Abstract

The effect of a detached breakwater, which was constructed to improve harbor tranquility inside Pohang New Port, was examined through the comparison of wave data measured before and after the construction of the breakwater. The observation data showed that the wave energy was [...] Read more.

The effect of a detached breakwater, which was constructed to improve harbor tranquility inside Pohang New Port, was examined through the comparison of wave data measured before and after the construction of the breakwater. The observation data showed that the wave energy was effectively reduced by the breakwater, although the wave height measured outside the breakwater was higher after its construction. The wave energy was reduced in all of the measured wave-propagating directions, but it was also observed that the breakwater became less effective in protecting against northeastwaves than in protecting against NNE waves. The BOUSS-2D Boussinesq-type wave model was employed to analyze the pattern of wave propagation, showing that, before the breakwater’s construction, NE waves could directly enter the port, increasing the wave energy inside the port. After the breakwater’s construction, simulations showed that the detached breakwater effectively blocked the waves approaching the port from both the NNE and NE directions, although the wave heights of the waves from the extreme NE direction inside the port increased. Considering that the estimated probability of failing to preserve the port tranquility was only 0.2–0.5% for these extreme NE waves, it was concluded that no secondary structures were necessary, and the existing breakwater was sufficient for the protection of the port. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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10 pages, 769 KiB

Open AccessTechnical Note

Influence of Van Gent Parameters on the Overtopping Discharge of a Rubble Mound Breakwater

by Federico Castiglione, Martina Stagnitti, Rosaria Ester Musumeci and Enrico Foti

J. Mar. Sci. Eng. 2023, 11(8), 1600; https://doi.org/10.3390/jmse11081600 - 16 Aug 2023

Cited by 1 | Viewed by 629

Abstract

The choice of the values of the friction parameters may strongly influence the numerical modeling of the interaction between waves and porous media. Here, an assessment of such an influence is carried out using the OpenFOAM solver IhFoamV1 to simulate the response of [...] Read more.

The choice of the values of the friction parameters may strongly influence the numerical modeling of the interaction between waves and porous media. Here, an assessment of such an influence is carried out using the OpenFOAM solver IhFoamV1 to simulate the response of the Catania harbor breakwater under extreme wave attack. The numerical model was validated by comparison with an experimental dataset, and a sensitivity analysis of the overtopping discharge estimate to van Gent parameter

β

was carried out testing values suggested by previous studies. A discussion on the importance of a careful estimate of such a parameter when dealing with the numerical modeling of porous coastal structures is presented. Indeed, variations in the non-dimensional overtopping discharge higher than 150% were observed as a consequence of a small variation (

10

–

20 %

) in the absolute value of

β

. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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17 pages, 4710 KiB

Open AccessCase Report

Climate Change Threats to Two Breakwaters

by William Allsop

J. Mar. Sci. Eng. 2022, 10(11), 1613; https://doi.org/10.3390/jmse10111613 - 01 Nov 2022

Viewed by 1363

Abstract

This paper illustrates by practical examples how designers/owners can analyse the potential effects of climate change on coastal structures. It presents two example structures: at Brighton Marina (Sussex, England) and La Collette reclamation (St Helier, Jersey). In both instances the results of Joint [...] Read more.

This paper illustrates by practical examples how designers/owners can analyse the potential effects of climate change on coastal structures. It presents two example structures: at Brighton Marina (Sussex, England) and La Collette reclamation (St Helier, Jersey). In both instances the results of Joint Probability Analysis are used to define test conditions, noting that these will be different for different responses. Whilst the solutions for climate change challenges to each structure are different, the paper illustrates example solutions that may be relatively easily deployed. Full article

(This article belongs to the Special Issue Advanced Studies in Breakwaters and Coastal Protection)

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