Pub Date : 2025-02-01DOI: 10.1016/j.coastaleng.2025.104715
Xuanlie Zhao , Shiqi Pan , Qingping Zou , Jing Geng
A 3D Reynolds-Averaged Navier-Stokes (RANS) flow solver with a Volume of Fluid (VOF) surface capturing scheme is used to investigate the dam-break flow induced slamming impacts on land-based oscillating water columns (OWC). Comprehensive experiments are conducted to validate the numerical model. It is found that the compressible RANS-VOF solver more accurately captures the key physical processes in this complex fluid-structure interaction process than the incompressible solver. The complete process of dam-break flow impact on OWCs is analyzed in detail, focusing on the relationship between peak forces, moments, slamming pressures, and fluid behaviors. It is found that the peaked vertical loads due to air pressure on the deck of the OWC chamber are non-negligible, particularly for small opening ratios (<3.5%), which has not been previously reported. Additionally, the air pressure on the deck significantly contributes to the moment of the OWC caisson. The distribution of slamming pressure on the front wall, corresponding to peak loading, resembles that of breaking waves in realistic seas. This implies that dam-break flow tests can be used to capture the fundamental physics behind the strong nonlinear waves interacting with OWCs. Numerical simulations are performed to examine the influence of the opening ratio of the OWC chamber on slamming characteristics. It is found that slamming loads on the OWC decrease rapidly with increasing opening ratio in from 0% to 3.5%. However, when the opening ratio exceeds the critical value of 3.5%, the slamming loads change only slightly. Furthermore, during the slamming process, the air pressure inside the chamber is proportional to the velocity of the water surface inside the chamber.
{"title":"Slamming loads induced by dam-break flow on land-based oscillating water columns: Numerical and experimental study","authors":"Xuanlie Zhao , Shiqi Pan , Qingping Zou , Jing Geng","doi":"10.1016/j.coastaleng.2025.104715","DOIUrl":"10.1016/j.coastaleng.2025.104715","url":null,"abstract":"<div><div>A 3D Reynolds-Averaged Navier-Stokes (RANS) flow solver with a Volume of Fluid (VOF) surface capturing scheme is used to investigate the dam-break flow induced slamming impacts on land-based oscillating water columns (OWC). Comprehensive experiments are conducted to validate the numerical model. It is found that the compressible RANS-VOF solver more accurately captures the key physical processes in this complex fluid-structure interaction process than the incompressible solver. The complete process of dam-break flow impact on OWCs is analyzed in detail, focusing on the relationship between peak forces, moments, slamming pressures, and fluid behaviors. It is found that the peaked vertical loads due to air pressure on the deck of the OWC chamber are non-negligible, particularly for small opening ratios (<3.5%), which has not been previously reported. Additionally, the air pressure on the deck significantly contributes to the moment of the OWC caisson. The distribution of slamming pressure on the front wall, corresponding to peak loading, resembles that of breaking waves in realistic seas. This implies that dam-break flow tests can be used to capture the fundamental physics behind the strong nonlinear waves interacting with OWCs. Numerical simulations are performed to examine the influence of the opening ratio of the OWC chamber on slamming characteristics. It is found that slamming loads on the OWC decrease rapidly with increasing opening ratio in from 0% to 3.5%. However, when the opening ratio exceeds the critical value of 3.5%, the slamming loads change only slightly. Furthermore, during the slamming process, the air pressure inside the chamber is proportional to the velocity of the water surface inside the chamber.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104715"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143351037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-31DOI: 10.1016/j.coastaleng.2025.104716
Mohammad Saidee Hasan , Ali Dastgheib , Arne van der Hout , Dano Roelvink
Due to the increase in ship sizes and traffic, the effect of passing ships on the mooring forces of moored ships is becoming an increasingly more important aspect in restricted waterways, channels, and ports. The objective of the presented work is to investigate the effects of the presence of an ambient current on the hydrodynamic forces on moored ships when another vessel passes through the waterway.
In this research, XBeach-NH in (nonhq3d) mode is used to simulate passing ship effects, corresponding to test conditions as measured in physical model tests carried out at Deltares as a part of the JIP Ropes (Joint Industry Project, Research on Passing Effects on Ships) project (van der Hout and de Jong, 2014). Even though various layouts were tested in the Ropes project; the current paper focuses on the straight channel layout with different combinations of ship velocity and ambient current speed. Results show that XBeach slightly overestimates the draw down effects (water level depression) due to the primary waves, as well as the surge forces. And, the differences in surge forces between XBeach and measurement increases with increasing Froude number. However, sway forces and yaw moments are in better agreement with the measured data, even for higher Froude numbers, though slightly underestimated. This variation in results is consistent in almost all XBeach simulations. Results also indicate that ship velocities relative through water are more important than ship speed over ground in the presence of uniform current. However, in modelling exercises, it is advisable to run simulations implementing actual currents rather than simply adding or subtracting the current velocity to/from ship speed over ground to obtain a representative relative vessel through water, since in the latter case the duration of hydrodynamic force excitation on the moored vessel will not be realistic. Furthermore, simulations show that by only representing the correct relative speed through water in the simulations (and not the correct speed over ground), the surge force & yaw moment magnitude are underestimated in case of counter currents and sway forces are underestimated in case of following currents.
{"title":"Ship-induced wave forces on a moored ship in the presence of uniform current","authors":"Mohammad Saidee Hasan , Ali Dastgheib , Arne van der Hout , Dano Roelvink","doi":"10.1016/j.coastaleng.2025.104716","DOIUrl":"10.1016/j.coastaleng.2025.104716","url":null,"abstract":"<div><div>Due to the increase in ship sizes and traffic, the effect of passing ships on the mooring forces of moored ships is becoming an increasingly more important aspect in restricted waterways, channels, and ports. The objective of the presented work is to investigate the effects of the presence of an ambient current on the hydrodynamic forces on moored ships when another vessel passes through the waterway.</div><div>In this research, XBeach-NH in (nonhq3d) mode is used to simulate passing ship effects, corresponding to test conditions as measured in physical model tests carried out at Deltares as a part of the JIP Ropes (Joint Industry Project, Research on Passing Effects on Ships) project (van der Hout and de Jong, 2014). Even though various layouts were tested in the Ropes project; the current paper focuses on the straight channel layout with different combinations of ship velocity and ambient current speed. Results show that XBeach slightly overestimates the draw down effects (water level depression) due to the primary waves, as well as the surge forces. And, the differences in surge forces between XBeach and measurement increases with increasing Froude number. However, sway forces and yaw moments are in better agreement with the measured data, even for higher Froude numbers, though slightly underestimated. This variation in results is consistent in almost all XBeach simulations. Results also indicate that ship velocities relative through water are more important than ship speed over ground in the presence of uniform current. However, in modelling exercises, it is advisable to run simulations implementing actual currents rather than simply adding or subtracting the current velocity to/from ship speed over ground to obtain a representative relative vessel through water, since in the latter case the duration of hydrodynamic force excitation on the moored vessel will not be realistic. Furthermore, simulations show that by only representing the correct relative speed through water in the simulations (and not the correct speed over ground), the surge force & yaw moment magnitude are underestimated in case of counter currents and sway forces are underestimated in case of following currents.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104716"},"PeriodicalIF":4.2,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143388066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1016/j.coastaleng.2025.104702
Gioele Ruffini , Riccardo Briganti , Jacob Stolle , Paolo De Girolamo
Tsunamis and other extreme hydrodynamic events have the potential to transport large debris that, along with the flow, are capable of causing severe damage to coastal structures and infrastructures. Therefore, modelling such processes is essential when assessing the multiple hazards associated to this type of events. In harbour areas, transport inland of shipping containers and subsequent impacts are relevant examples of waterborne debris hazards. The present work addresses two gaps in the scientific research of this problem using numerical methods; the understanding of the effect of containers initial layouts and that of the flow impact angle on the transport and diffusion. To fill these gaps a numerical study was carried out using idealised flow conditions. To this end a Smoothed Particles Hydrodynamics solver (DualSPHysics), coupled with a Discrete Element Method model (Project CHRONO), was used and initially validated with experiments published in the literature. Subsequently, four layouts commonly used in shipping containers yards were simulated, including incident flow depth and impact angle variability, resulting in 76 total simulations. The results were analysed in terms of normalised standard deviation and normalised range differences with respect to the initial values of both parameters. These parameters were related to the flow impact angle, water depth to containers height ratio , and normalised displacement of the container clusters centroids. Standard deviation and range are shown to reach, for almost all results, a quasi-steady state by the end of the simulations. It is shown that the standard deviation and range are more sensitive to the impact angle for . In this case, the configurations with flow impacting orthogonally to one of the containers axes show larger values of the two parameters than for intermediate angles. For larger values, drives the standard deviation and range, independently from the impact angle. is shown to be a physical parameter that well describes the relative importance of dispersion and advection of containers transported in extreme hydrodynamic events. Finally, existing relationships, that assume an infinite growth of the range, are shown to overestimate numerical results at the stage in which dispersion does not grow further. Two new regression formulae are numerically derived to predict the dispersion parameters at this stage. They include the effects of the cluster layout, impact angle and making them a valid alternative to existing relationships.
{"title":"Numerical analysis and prediction of the effect of debris initial configurations on their dispersion during extreme-hydrodynamic events","authors":"Gioele Ruffini , Riccardo Briganti , Jacob Stolle , Paolo De Girolamo","doi":"10.1016/j.coastaleng.2025.104702","DOIUrl":"10.1016/j.coastaleng.2025.104702","url":null,"abstract":"<div><div>Tsunamis and other extreme hydrodynamic events have the potential to transport large debris that, along with the flow, are capable of causing severe damage to coastal structures and infrastructures. Therefore, modelling such processes is essential when assessing the multiple hazards associated to this type of events. In harbour areas, transport inland of shipping containers and subsequent impacts are relevant examples of waterborne debris hazards. The present work addresses two gaps in the scientific research of this problem using numerical methods; the understanding of the effect of containers initial layouts and that of the flow impact angle on the transport and diffusion. To fill these gaps a numerical study was carried out using idealised flow conditions. To this end a Smoothed Particles Hydrodynamics solver (DualSPHysics), coupled with a Discrete Element Method model (Project CHRONO), was used and initially validated with experiments published in the literature. Subsequently, four layouts commonly used in shipping containers yards were simulated, including incident flow depth and impact angle variability, resulting in 76 total simulations. The results were analysed in terms of normalised standard deviation and normalised range differences with respect to the initial values of both parameters. These parameters were related to the flow impact angle, water depth to containers height ratio <span><math><mrow><mi>D</mi><mi>h</mi><mi>R</mi></mrow></math></span>, and normalised displacement of the container clusters centroids. Standard deviation and range are shown to reach, for almost all results, a quasi-steady state by the end of the simulations. It is shown that the standard deviation and range are more sensitive to the impact angle for <span><math><mrow><mi>D</mi><mi>h</mi><mi>R</mi><mo>≤</mo><mn>1</mn><mo>.</mo><mn>7</mn></mrow></math></span>. In this case, the configurations with flow impacting orthogonally to one of the containers axes show larger values of the two parameters than for intermediate angles. For larger values, <span><math><mrow><mi>D</mi><mi>h</mi><mi>R</mi></mrow></math></span> drives the standard deviation and range, independently from the impact angle. <span><math><mrow><mi>D</mi><mi>h</mi><mi>R</mi></mrow></math></span> is shown to be a physical parameter that well describes the relative importance of dispersion and advection of containers transported in extreme hydrodynamic events. Finally, existing relationships, that assume an infinite growth of the range, are shown to overestimate numerical results at the stage in which dispersion does not grow further. Two new regression formulae are numerically derived to predict the dispersion parameters at this stage. They include the effects of the cluster layout, impact angle <span><math><mi>α</mi></math></span> and <span><math><mrow><mi>D</mi><mi>h</mi><mi>R</mi></mrow></math></span> making them a valid alternative to existing relationships.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104702"},"PeriodicalIF":4.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.coastaleng.2025.104705
Maximilian Herbst , Nils B. Kerpen , Talia Schoonees , Torsten Schlurmann
Stepped revetments are known to be more effective in limiting wave overtopping and wave run-up than sloped revetments. However, literature on wave-induced impact pressures and comprehensive guidelines on the practical design for these structures is scarce. Laboratory experiments support the development of design recommendations. To date, studies for wave impacts at stepped revetments have mainly been carried out at small scales. This study characterizes wave-induced impact pressures at full scale, derives practical design formulae and evaluates findings against established methods for vertical walls and sloping structures. Additionally, an insight into the influence of scale is given by comparing wave impact characteristics for design cases between tests at multiple scales. Flume experiments with a slope of 1:3 and uniform step heights of 0.17 m and 0.50 m were investigated in the Large Wave Flume (GWK) in Hannover, Germany. Horizontal and vertical wave-induced pressure impacts were measured at 15 distinct locations for a large range of wave-breaking types (1.8 < ξm-1,0 < 2.8). Wave impact characteristics on stepped revetments align more closely with those observed on vertical walls than on sloped structures. Horizontal impacts are dominant over vertical impacts across the entire tested parameter range and thus critical for design considerations. Results show that previous small-scale tests significantly overestimate the maximum wave-induced impact pressures by a factor of 5.0 and maximum forces by a factor of 2.4. Impact loads occur significantly faster than at small scale. Design quasi-static pressures above the still-water level can be calculated and maximum horizontal impact pressures can be scaled using existing methods for vertical walls. Practical design formulae are derived for horizontal and vertical design pressures for different types of wave-breaking, for the vertical distribution of horizontal wave-induced impact pressures as well as for the temporal characteristics of these pressures at stepped revetments.
{"title":"Full-scale experimental study on wave impacts at stepped revetments","authors":"Maximilian Herbst , Nils B. Kerpen , Talia Schoonees , Torsten Schlurmann","doi":"10.1016/j.coastaleng.2025.104705","DOIUrl":"10.1016/j.coastaleng.2025.104705","url":null,"abstract":"<div><div>Stepped revetments are known to be more effective in limiting wave overtopping and wave run-up than sloped revetments. However, literature on wave-induced impact pressures and comprehensive guidelines on the practical design for these structures is scarce. Laboratory experiments support the development of design recommendations. To date, studies for wave impacts at stepped revetments have mainly been carried out at small scales. This study characterizes wave-induced impact pressures at full scale, derives practical design formulae and evaluates findings against established methods for vertical walls and sloping structures. Additionally, an insight into the influence of scale is given by comparing wave impact characteristics for design cases between tests at multiple scales. Flume experiments with a slope of 1:3 and uniform step heights of 0.17 m and 0.50 m were investigated in the Large Wave Flume (GWK) in Hannover, Germany. Horizontal and vertical wave-induced pressure impacts were measured at 15 distinct locations for a large range of wave-breaking types (1.8 < ξ<sub>m-1,0</sub> < 2.8). Wave impact characteristics on stepped revetments align more closely with those observed on vertical walls than on sloped structures. Horizontal impacts are dominant over vertical impacts across the entire tested parameter range and thus critical for design considerations. Results show that previous small-scale tests significantly overestimate the maximum wave-induced impact pressures by a factor of 5.0 and maximum forces by a factor of 2.4. Impact loads occur significantly faster than at small scale. Design quasi-static pressures above the still-water level can be calculated and maximum horizontal impact pressures can be scaled using existing methods for vertical walls. Practical design formulae are derived for horizontal and vertical design pressures for different types of wave-breaking, for the vertical distribution of horizontal wave-induced impact pressures as well as for the temporal characteristics of these pressures at stepped revetments.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104705"},"PeriodicalIF":4.2,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.coastaleng.2025.104704
Ruicong Wu , Anxin Guo , Sijia Zhu , Jiabin Liu
This study experimentally investigated the growth of wind-driven waves under uniform currents. The wind-driven wave spatiotemporal evolution characteristics were collected along the fetch, and visual techniques were used to measure the phase velocity and flow field characteristics. Based on the experimental results, the variation patterns of dimensionless peak frequency and energy over time and space were analyzed, and their relationships with the dimensionless current velocity, fetch, and wave age were determined. The currents significantly influence the trend in dimensionless energy, with their effect on peak frequency and dimensionless energy primarily reflected in the exponential term. The exponent coefficient of peak frequency for the co-current is approximately , while for the counter-current, it is , where is the current velocity, is the wind friction velocity, and is the dimensionless fetch. Both co- and counter-currents increase the turbulent kinetic energy. The co-current minimally affects the velocity field distribution, with the Q4 quadrant dominating in the quadrant analysis. In contrast, the counter-current significantly alters the velocity field, shifting the Reynolds stress dominance from Q4 to Q2 and resulting in a more evenly distributed four-quadrant pattern, enhancing the upward momentum transfer. These changes in momentum transfer significantly affect the spatiotemporal evolution of wind-driven waves under uniform currents.
{"title":"Growth of wind-driven waves under uniform currents","authors":"Ruicong Wu , Anxin Guo , Sijia Zhu , Jiabin Liu","doi":"10.1016/j.coastaleng.2025.104704","DOIUrl":"10.1016/j.coastaleng.2025.104704","url":null,"abstract":"<div><div>This study experimentally investigated the growth of wind-driven waves under uniform currents. The wind-driven wave spatiotemporal evolution characteristics were collected along the fetch, and visual techniques were used to measure the phase velocity and flow field characteristics. Based on the experimental results, the variation patterns of dimensionless peak frequency and energy over time and space were analyzed, and their relationships with the dimensionless current velocity, fetch, and wave age were determined. The currents significantly influence the trend in dimensionless energy, with their effect on peak frequency and dimensionless energy primarily reflected in the exponential term. The exponent coefficient of peak frequency for the co-current is approximately <span><math><mrow><msub><mi>U</mi><mi>c</mi></msub><mo>/</mo><msup><mi>u</mi><mo>∗</mo></msup></mrow></math></span>, while for the counter-current, it is <span><math><mrow><mn>6</mn><msup><mi>χ</mi><mrow><mo>∗</mo><mo>−</mo><mn>0.26</mn></mrow></msup><msub><mi>U</mi><mi>c</mi></msub><mo>/</mo><msup><mi>u</mi><mo>∗</mo></msup></mrow></math></span>, where <span><math><mrow><msub><mi>U</mi><mi>c</mi></msub></mrow></math></span> is the current velocity, <span><math><mrow><msup><mi>u</mi><mo>∗</mo></msup></mrow></math></span> is the wind friction velocity, and <span><math><mrow><msup><mi>χ</mi><mo>∗</mo></msup></mrow></math></span> is the dimensionless fetch. Both co- and counter-currents increase the turbulent kinetic energy. The co-current minimally affects the velocity field distribution, with the Q4 quadrant dominating in the quadrant analysis. In contrast, the counter-current significantly alters the velocity field, shifting the Reynolds stress dominance from Q4 to Q2 and resulting in a more evenly distributed four-quadrant pattern, enhancing the upward momentum transfer. These changes in momentum transfer significantly affect the spatiotemporal evolution of wind-driven waves under uniform currents.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104704"},"PeriodicalIF":4.2,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.coastaleng.2025.104703
Jiale Li , Jijian Lian , Yaohua Guo , Xiaofeng Dong , Yang Gao
The multi-bucket jacket foundations (MBJF) have been extensively applied in offshore wind farms in China. Scour significantly affects the in-situ stability of wide and shallow MBJF, but existing scour protection methods fail to adequately account for the structural and construction characteristics of wide, shallow buckets and their suction installation. Thus, their applicability to MBJF in harsh marine environments is limited. This study has proposed a pre-embedded protection method (referring to the placement of the bucket lid below the seabed to enhance the stability and safety of the foundation under scouring conditions) and designed detailed experiments. A 3D structured light depth measurement technique was employed to capture terrain morphology, and high-resolution elevation images were generated using point cloud reconstruction for scour analysis and statistics. This study has revealed the influence patterns of the lid elevation, inflow angle, flow intensity, and water depth on the current-induced scour characteristics and protection efficiency of MBJF with pre-embedded protection. Based on model test results, predictive formulas for maximum scour depth and scour extent under pre-embedded protection were derived and refined. The results indicate that pre-embedded protection measures are highly efficient under various lid elevations, inflow angles, flow intensities, and water depths. Notably, flow intensity is the most sensitive factor influencing scour characteristics. An increase in embedded depth reduces both maximum scour depth and scour extent, with protection efficiency reaching up to 52% and 70.1%, respectively, in certain cases. An extreme angle that generates the greatest scour depth is identified, which is 30° under the current experimental conditions. Moreover, an increase in flow intensity and a decrease in water depth both lead to an increase in scour depth, especially under live-bed scour conditions. These findings are of great significance for enhancing the stability and long-term operational safety of offshore wind turbine foundations, providing methodological and theoretical support for scour protection of similar foundations.
{"title":"Experimental study on current-induced local scour and pre-embedded protective measures of multi-bucket jacket foundation for offshore wind turbines","authors":"Jiale Li , Jijian Lian , Yaohua Guo , Xiaofeng Dong , Yang Gao","doi":"10.1016/j.coastaleng.2025.104703","DOIUrl":"10.1016/j.coastaleng.2025.104703","url":null,"abstract":"<div><div>The multi-bucket jacket foundations (MBJF) have been extensively applied in offshore wind farms in China. Scour significantly affects the in-situ stability of wide and shallow MBJF, but existing scour protection methods fail to adequately account for the structural and construction characteristics of wide, shallow buckets and their suction installation. Thus, their applicability to MBJF in harsh marine environments is limited. This study has proposed a pre-embedded protection method (referring to the placement of the bucket lid below the seabed to enhance the stability and safety of the foundation under scouring conditions) and designed detailed experiments. A 3D structured light depth measurement technique was employed to capture terrain morphology, and high-resolution elevation images were generated using point cloud reconstruction for scour analysis and statistics. This study has revealed the influence patterns of the lid elevation, inflow angle, flow intensity, and water depth on the current-induced scour characteristics and protection efficiency of MBJF with pre-embedded protection. Based on model test results, predictive formulas for maximum scour depth and scour extent under pre-embedded protection were derived and refined. The results indicate that pre-embedded protection measures are highly efficient under various lid elevations, inflow angles, flow intensities, and water depths. Notably, flow intensity is the most sensitive factor influencing scour characteristics. An increase in embedded depth reduces both maximum scour depth and scour extent, with protection efficiency reaching up to 52% and 70.1%, respectively, in certain cases. An extreme angle that generates the greatest scour depth is identified, which is 30° under the current experimental conditions. Moreover, an increase in flow intensity and a decrease in water depth both lead to an increase in scour depth, especially under live-bed scour conditions. These findings are of great significance for enhancing the stability and long-term operational safety of offshore wind turbine foundations, providing methodological and theoretical support for scour protection of similar foundations.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104703"},"PeriodicalIF":4.2,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper reports on numerical simulations of focused waves on currents interacting with a vertical cylinder. The simulations are conducted using a Numerical Wave Tank (NWT) based on the method of Large Eddy Simulations (LES). Experimental data are utilised to validate the NWT’s ability to reproduce accurately the wave–current kinematics for a following, an opposing and no current case, all under the same wave condition. The LES-predicted results in terms of wave elevations and velocities under wave crest and trough agree well with the experimental data for all conditions. The instantaneous and mean velocity field at various locations and current conditions as well as three-dimensional visualisations using isosurfaces of the Q-criterion showcase the complexity of the wave–current-cylinder interactions which is manifested in turbulence structures near the cylinder in the form of the horseshoe vortex, flow separation vortices as well as shear layer vortices in the cylinder wake. The effect of the focused wave on the distribution of the wall shear stress in the vicinity of the cylinder is quantified: while the overall distribution of the wall shear stress is similar with and without waves, the wall shear stress attains substantially higher values locally, up to 80 times, when the focused wave passes by than in the shear current only scenario.
{"title":"Focused waves on shear currents interacting with a vertical cylinder","authors":"Aristos Christou , Dimitris Stagonas , Eugeny Buldakov , Thorsten Stoesser","doi":"10.1016/j.coastaleng.2025.104698","DOIUrl":"10.1016/j.coastaleng.2025.104698","url":null,"abstract":"<div><div>This paper reports on numerical simulations of focused waves on currents interacting with a vertical cylinder. The simulations are conducted using a Numerical Wave Tank (NWT) based on the method of Large Eddy Simulations (LES). Experimental data are utilised to validate the NWT’s ability to reproduce accurately the wave–current kinematics for a following, an opposing and no current case, all under the same wave condition. The LES-predicted results in terms of wave elevations and velocities under wave crest and trough agree well with the experimental data for all conditions. The instantaneous and mean velocity field at various locations and current conditions as well as three-dimensional visualisations using isosurfaces of the Q-criterion showcase the complexity of the wave–current-cylinder interactions which is manifested in turbulence structures near the cylinder in the form of the horseshoe vortex, flow separation vortices as well as shear layer vortices in the cylinder wake. The effect of the focused wave on the distribution of the wall shear stress in the vicinity of the cylinder is quantified: while the overall distribution of the wall shear stress is similar with and without waves, the wall shear stress attains substantially higher values locally, up to 80 times, when the focused wave passes by than in the shear current only scenario.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104698"},"PeriodicalIF":4.2,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-20DOI: 10.1016/j.coastaleng.2025.104700
Massimiliano Marino, Sofia Nasca, Ahmad IK Alkharoubi, Luca Cavallaro, Enrico Foti, Rosaria Ester Musumeci
Nature-based Solutions (NbS) are emerging as sustainable alternatives to conventional coastal defences against flooding and erosion. However, modelling applications to assess their efficacy often employ deterministic approaches based on historical storms, seldom incorporating effects of climate change. We argue that assessing coastal NbS performance for current and future scenarios is essential to ensure their long-term efficacy, adaptability, and potential synergies with climate adaptation and mitigation strategies. To this aim, we propose a modelling framework to investigate effectiveness of Nature-based coastal defences to mitigate climate change-driven, storm-induced flooding and erosion. An hydro-morphodynamic modelling chain (SWAN and XBeach) is setup to evaluate the effectiveness of two interventions — a dune revegetation and a seagrass meadow reconstruction — in reducing coastal inundation and shoreline retreat. The study investigates present and future what-if scenarios, by simulating storm conditions based on present, 4.5, and 8.5 W/m2 radiative forcing scenarios. Dissipative effects of vegetation are modelled by providing their characteristics and spatial distribution through habitat maps. Simple flooding and erosion reduction efficacy indicators are computed to support the assessment. The approach is applied to a case study along the Sicily coast (Italy). Results reveal that the vulnerability of the area to flooding is predominantly driven by sea level rise rather than by increase in significant wave height. In this regard, both considered interventions effectively reduce flooded areas across all investigated scenarios up to 66%, while the reconstruction of the seagrass meadow also significantly reduces storm-driven eroded volumes. Its efficacy however is less significant under 2100-time horizon scenarios, underscoring the need for NbS strategies that may be flexible and responsive to changing climate conditions.
{"title":"Efficacy of Nature-based Solutions for coastal protection under a changing climate: A modelling approach","authors":"Massimiliano Marino, Sofia Nasca, Ahmad IK Alkharoubi, Luca Cavallaro, Enrico Foti, Rosaria Ester Musumeci","doi":"10.1016/j.coastaleng.2025.104700","DOIUrl":"10.1016/j.coastaleng.2025.104700","url":null,"abstract":"<div><div>Nature-based Solutions (NbS) are emerging as sustainable alternatives to conventional coastal defences against flooding and erosion. However, modelling applications to assess their efficacy often employ deterministic approaches based on historical storms, seldom incorporating effects of climate change. We argue that assessing coastal NbS performance for current and future scenarios is essential to ensure their long-term efficacy, adaptability, and potential synergies with climate adaptation and mitigation strategies. To this aim, we propose a modelling framework to investigate effectiveness of Nature-based coastal defences to mitigate climate change-driven, storm-induced flooding and erosion. An hydro-morphodynamic modelling chain (SWAN and XBeach) is setup to evaluate the effectiveness of two interventions — a dune revegetation and a seagrass meadow reconstruction — in reducing coastal inundation and shoreline retreat. The study investigates present and future what-if scenarios, by simulating storm conditions based on present, 4.5, and 8.5 W/m<sup>2</sup> radiative forcing scenarios. Dissipative effects of vegetation are modelled by providing their characteristics and spatial distribution through habitat maps. Simple flooding and erosion reduction efficacy indicators are computed to support the assessment. The approach is applied to a case study along the Sicily coast (Italy). Results reveal that the vulnerability of the area to flooding is predominantly driven by sea level rise rather than by increase in significant wave height. In this regard, both considered interventions effectively reduce flooded areas across all investigated scenarios up to 66%, while the reconstruction of the seagrass meadow also significantly reduces storm-driven eroded volumes. Its efficacy however is less significant under 2100-time horizon scenarios, underscoring the need for NbS strategies that may be flexible and responsive to changing climate conditions.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"198 ","pages":"Article 104700"},"PeriodicalIF":4.2,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143139201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.coastaleng.2025.104697
Davina L. Passeri , Rangley C. Mickey , David M. Thompson , Michael Itzkin , Elizabeth Godsey , Matthew V. Bilskie , Alexander Seymour , Autumn Poisson , Jin Ikeda , Scott C. Hagen
This study assesses the impacts of five proposed restoration actions at Little Dauphin Island, a low-lying relic spit in a semi-enclosed bay system on the Alabama coast. A Delft3D model is developed to simulate annual scale (five-year) sediment transport and resulting bed level changes. The model is validated with observed water level and wave data, as well as sediment tracers that were deployed offshore of the island. An XBeach model is developed to simulate storm-driven morphologic change and is validated for hurricanes Ivan (2004), Katrina (2005)and Sally (2020). Together, the models are used to assess differences in the island's morphological response under a no-action (status quo) scenario representing a continuous island, tidal inlet realignment, a sand motor nourishment, beach and dune restoration and a dredged offshore borrow area. The no-action scenario revealed that the island breached at multiple locations including the location of the proposed inlet realignment during each storm. The realigned channel did not prevent breaching on the island, but reduced the magnitude of sand transported through the breaches. The sand motor provided some sheltering to leeward shorelines during storms but did not prevent breaching from occurring elsewhere. Fairweather waves and currents were not strong enough to transport sand outside of the vicinity of the feature to feed adjacent shorelines as intended. The beach and dune restoration reduced storm-driven overtopping along the nourished shoreline. For habitat purposes, strategically placed bayous provided low elevation points that allowed overwash depending on the direction of cross-barrier water level gradients.
{"title":"Modeling the impacts of sand placement strategies on barrier island evolution in a semi-enclosed bay system","authors":"Davina L. Passeri , Rangley C. Mickey , David M. Thompson , Michael Itzkin , Elizabeth Godsey , Matthew V. Bilskie , Alexander Seymour , Autumn Poisson , Jin Ikeda , Scott C. Hagen","doi":"10.1016/j.coastaleng.2025.104697","DOIUrl":"10.1016/j.coastaleng.2025.104697","url":null,"abstract":"<div><div>This study assesses the impacts of five proposed restoration actions at Little Dauphin Island, a low-lying relic spit in a semi-enclosed bay system on the Alabama coast. A Delft3D model is developed to simulate annual scale (five-year) sediment transport and resulting bed level changes. The model is validated with observed water level and wave data, as well as sediment tracers that were deployed offshore of the island. An XBeach model is developed to simulate storm-driven morphologic change and is validated for hurricanes Ivan (2004), Katrina (2005)and Sally (2020). Together, the models are used to assess differences in the island's morphological response under a no-action (status quo) scenario representing a continuous island, tidal inlet realignment, a sand motor nourishment, beach and dune restoration and a dredged offshore borrow area. The no-action scenario revealed that the island breached at multiple locations including the location of the proposed inlet realignment during each storm. The realigned channel did not prevent breaching on the island, but reduced the magnitude of sand transported through the breaches. The sand motor provided some sheltering to leeward shorelines during storms but did not prevent breaching from occurring elsewhere. Fairweather waves and currents were not strong enough to transport sand outside of the vicinity of the feature to feed adjacent shorelines as intended. The beach and dune restoration reduced storm-driven overtopping along the nourished shoreline. For habitat purposes, strategically placed bayous provided low elevation points that allowed overwash depending on the direction of cross-barrier water level gradients.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"197 ","pages":"Article 104697"},"PeriodicalIF":4.2,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1016/j.coastaleng.2025.104699
Sergio Muñoz-Palao , Pilar Díaz-Carrasco , Jorge Molines , M. Esther Gómez-Martín , Josep R. Medina
Mechanical profilers are commonly used to measure damage to rubble mound breakwaters in small-scale physical tests. This study developed a non-intrusive methodology using low-cost 3D depth-sensors to measure damage progression in Homogeneous Low-Crested Structures (HLCS) with and without water in the wave flume. Although light refraction causes distortion in the presence of water, distorted scans are corrected with this new method using a Neural Network (NN) model. The new methodology is adequate to obtain undistorted profiles of emerged or submerged breakwaters and may be described in two steps: (1) a digital profiler algorithm, to describe the breakwater models in series of profiles in order to measure damage, and (2) a trained NN model, to correct the distortions caused by light refraction for the scans taken with water in the wave flume. The NN model to correct profiles requires two sets of scans, one in empty conditions and the other in submerged conditions; the two scans (dry-wet) can be easily obtained without disturbing the usual test programs. This is done by taking the scans at the beginning (dry and wet) and at the end (wet and dry) of each test series. By comparing profiles, the breakwater damage can be analysed after obtaining the series of undistorted profiles from the trained NN model and the distorted scans. To validate the method, a series of small-scale physical tests with Cubipod HLCS were carried out from no damage to severe damage, and then the estimations given by the trained NN models were compared with blind observations, taken from additional pairs of dry and wet scans. The good agreement between the observations and the estimations (R2 > 0.985, r > 0.993) showed that low-cost 3D depth-sensors may be used as non-intrusive methods for breakwater profiling, even when scanning is done with water in the wave flume or basin.
{"title":"A new method to measure damage progression in Homogeneous Low-Crested Structures with a low-cost 3D depth-sensor","authors":"Sergio Muñoz-Palao , Pilar Díaz-Carrasco , Jorge Molines , M. Esther Gómez-Martín , Josep R. Medina","doi":"10.1016/j.coastaleng.2025.104699","DOIUrl":"10.1016/j.coastaleng.2025.104699","url":null,"abstract":"<div><div>Mechanical profilers are commonly used to measure damage to rubble mound breakwaters in small-scale physical tests. This study developed a non-intrusive methodology using low-cost 3D depth-sensors to measure damage progression in Homogeneous Low-Crested Structures (HLCS) with and without water in the wave flume. Although light refraction causes distortion in the presence of water, distorted scans are corrected with this new method using a Neural Network (NN) model. The new methodology is adequate to obtain undistorted profiles of emerged or submerged breakwaters and may be described in two steps: (1) a digital profiler algorithm, to describe the breakwater models in series of profiles in order to measure damage, and (2) a trained NN model, to correct the distortions caused by light refraction for the scans taken with water in the wave flume. The NN model to correct profiles requires two sets of scans, one in empty conditions and the other in submerged conditions; the two scans (dry-wet) can be easily obtained without disturbing the usual test programs. This is done by taking the scans at the beginning (dry and wet) and at the end (wet and dry) of each test series. By comparing profiles, the breakwater damage can be analysed after obtaining the series of undistorted profiles from the trained NN model and the distorted scans. To validate the method, a series of small-scale physical tests with Cubipod HLCS were carried out from no damage to severe damage, and then the estimations given by the trained NN models were compared with blind observations, taken from additional pairs of dry and wet scans. The good agreement between the observations and the estimations (<em>R</em><sup><em>2</em></sup> > 0.985, <em>r</em> > 0.993) showed that low-cost 3D depth-sensors may be used as non-intrusive methods for breakwater profiling, even when scanning is done with water in the wave flume or basin.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"197 ","pages":"Article 104699"},"PeriodicalIF":4.2,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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