Coastal EngineeringPub Date : 2025-08-30DOI: 10.1016/j.coastaleng.2025.104868
Hunter Boswell , Frank D. Han , Guirong Yan , Wouter Mostert
{"title":"Energetics analysis of solitary waves using a multi-layer model","authors":"Hunter Boswell , Frank D. Han , Guirong Yan , Wouter Mostert","doi":"10.1016/j.coastaleng.2025.104868","DOIUrl":"10.1016/j.coastaleng.2025.104868","url":null,"abstract":"<div><div>This study investigates the performance of a vertically-Lagrangian multi-layer model on numerically simulating shoaling and breaking two-dimensional solitary waves during both the breaking and post-breaking processes. The energy dissipation of the breaking event for the multi-layer waves is analyzed and compared to prior direct numerical simulation work with the same bathymetric and wave cases. It shows very similar data collapse to shallow-water inertial theory. For post-breaking behavior, bore characteristics are compared to an experimental study of bores formed from breaking solitary waves and similar results are found. While the multi-layer method was not found to behave sufficiently well for direct force measurement at a vertical wall, the resulting bore characteristic behavior is found to be sufficient for use in theoretical estimations of the impact force on the wall. These findings in this study suggest that vertically-Lagrangian multilayer models resolve propagating bores sufficiently well when trying to estimate dynamic loads on vertical seawalls with minimal model tuning.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"203 ","pages":"Article 104868"},"PeriodicalIF":4.5,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145049330","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}
Coastal EngineeringPub Date : 2025-08-30DOI: 10.1016/j.coastaleng.2025.104871
Jianjun Huang , Ryan J. Lowe , Marco Ghisalberti , Jeff E. Hansen , Corrado Altomare
{"title":"Numerical study of wave-structure interactions with porous artificial reefs using Smoothed Particle Hydrodynamics","authors":"Jianjun Huang , Ryan J. Lowe , Marco Ghisalberti , Jeff E. Hansen , Corrado Altomare","doi":"10.1016/j.coastaleng.2025.104871","DOIUrl":"10.1016/j.coastaleng.2025.104871","url":null,"abstract":"<div><div>Porous artificial reefs are increasingly being used for nature-based coastal protection, given their ability to attenuate waves while providing habitat for marine species. The wave attenuation and ecological functions of porous artificial reefs depend on how wave-driven flows interact with the porous interior structure of a reef; however, these hydrodynamic processes are still relatively poorly understood. To overcome the challenges with resolving the detailed flow-structure interactions within porous artificial reefs at fine (order mm) spatial resolution, this study utilized a mesh-free Computational Fluid Dynamics modelling approach based on Smoothed Particle Hydrodynamics (SPH) using the DualSPHysics solver. The capability of the SPH model to accurately reproduce the reef hydrodynamics (including wave transformation, hydrodynamic forces acting on the structure, and drag and inertia coefficients) was first validated against three independent experimental datasets of wave-structure interactions. The model was then used in a two-dimensional (2D) numerical investigation of wave-structure interactions with porous artificial reefs, where the 3D geometric parameters of the reef structure were adjusted within the 2D model to properly account for the hydrodynamic forces within the reef (i.e., using a quasi-3D approach). The results reveal how the porous reefs modify the dynamics of wave-induced oscillatory flows within the reef structure that are responsible for generating horizontal and vertical drag forces, wave dissipation, turbulent kinetic energy, and mean currents. Drag coefficients decreased with the Keulegan-Carpenter number, with vertical drag coefficients typically larger than horizontal values. Wave dissipation across the porous reefs was due to a combination of horizontal drag forces and wave breaking, with vertical drag forces playing only a secondary role. Compared to less porous structures, the enhanced drag dissipation in porous artificial reefs enables them to attenuate waves more effectively over a greater range of water levels. Finally, the findings of this study underscore the potential for SPH models to be used as a cost-effective tool to support the design of porous artificial reefs for coastal protection.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"203 ","pages":"Article 104871"},"PeriodicalIF":4.5,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989366","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}
Coastal EngineeringPub Date : 2025-08-29DOI: 10.1016/j.coastaleng.2025.104857
Guillaume Coulaud , Maria Teles , Michel Benoit
{"title":"Numerical modelling of nearshore wave transformation, breaking and overtopping of coastal protections with the enhanced Serre–Green–Naghdi equations","authors":"Guillaume Coulaud , Maria Teles , Michel Benoit","doi":"10.1016/j.coastaleng.2025.104857","DOIUrl":"10.1016/j.coastaleng.2025.104857","url":null,"abstract":"<div><div>Admissible average overtopping discharges in given storm conditions are typically used to design coastal protections, in particular dykes or breakwaters. These discharges are usually estimated using semi-empirical formulas relying on wave conditions at the toe of the structure. These formulas, unfortunately, only work for simple configurations, invariant alongshore, and can be insufficient for complex sea states. Therefore, numerical modelling could be a more flexible alternative for estimating these discharges. This work presents the development and validation of a Boussinesq-type numerical model solving the fully-nonlinear weakly-dispersive enhanced Serre–Green–Naghdi equations for the simulation of random wave overtopping over impermeable structures in one horizontal dimension. Wave breaking is modelled with an eddy viscosity approach based on the turbulent kinetic energy, which is robust and accurate at describing energy dissipation in the surf zone. Two distinct experimental datasets, with 184 trials in total and very dissimilar wave conditions and foreshore seabed profiles, are used to validate the model regarding wave propagation, shoaling, breaking and overtopping. Both unimodal and bimodal sea states are considered. Average overtopping discharges in configurations with deep and very shallow foreshores, as well as for breaking and non-breaking waves, are well reproduced by the model. For instance, typical mean relative errors on the simulated mean overtopping rates are found to lie within <span><math><mrow><mo>±</mo><mn>20</mn><mtext>%</mtext></mrow></math></span> compared with the measurements, at least for the largest discharges of the considered campaigns. The scatter of simulated discharges is somewhat higher for lower discharges, but the results remain in an acceptable range.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"203 ","pages":"Article 104857"},"PeriodicalIF":4.5,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144933370","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}
Coastal EngineeringPub Date : 2025-08-23DOI: 10.1016/j.coastaleng.2025.104860
Yu Hsiao , Yun-Ta Wu
{"title":"Runup, inundation, and flow velocity of non-decaying dam-break bores on coarse-grained slopes","authors":"Yu Hsiao , Yun-Ta Wu","doi":"10.1016/j.coastaleng.2025.104860","DOIUrl":"10.1016/j.coastaleng.2025.104860","url":null,"abstract":"<div><div>This study investigates the swash flows generated by non-decaying dam-break bores traveling over permeable coarse-grained and impermeable beaches. Experiments were conducted to measure runup height, inundation depth, flow velocity, and variations in groundwater. The experiments covered a wide range of bore strengths, which is beneficial for systematically examining bore hydrodynamics, including their effects on runup and inundation. Then, comparisons were extended to the measured results on permeable and impermeable slopes. In this context, empirical formulations, originally developed for smooth and rough impermeable slopes, were refined with reduction factors derived from measurements on coarse-grained beaches, thus allowing for quantifying beach permeability effects. The reduction factors derived from the measured runup heights and inundation depths demonstrated a dependency on the bore types. Velocity fields within the surf and swash zones were captured using time-resolved particle image velocimetry, from which bed shear stresses were subsequently calculated. Four distinct stages of flow behavior were identified: uprush, first downrush, stagnant phase, and second downrush. During the flow reversal phase, it was observed that velocities near the bed reversed direction sooner than those nearer to the free surface, a phenomenon attributed to the boundary layer effect. In permeable slope cases, exfiltration processes became significant during the latter two stages of swash motion. The bed shear stresses, estimated using two distinct formulations, generally exhibited comparable trends. The mechanisms governing groundwater flow also differed between the two permeable beach types: on the gravel slope, bore-induced infiltration advances laterally and rapidly merges with the groundwater level; on the coarse sand beach, infiltration was primarily driven by gravitational drainage during the uprush phase.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"203 ","pages":"Article 104860"},"PeriodicalIF":4.5,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144907487","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}
Coastal EngineeringPub Date : 2025-08-22DOI: 10.1016/j.coastaleng.2025.104859
C.O. van IJzendoorn , M.E. Wengrove , P. Ruggiero , H.G. Bond
{"title":"Measurements and modeling of aeolian sand transport on dynamic cobble berm revetments","authors":"C.O. van IJzendoorn , M.E. Wengrove , P. Ruggiero , H.G. Bond","doi":"10.1016/j.coastaleng.2025.104859","DOIUrl":"10.1016/j.coastaleng.2025.104859","url":null,"abstract":"<div><div>Dynamic cobble berm revetments are a nature-based adaptation solution aimed at preventing or slowing coastal erosion. Dynamic cobble berm revetments mimic natural composite beaches that consist of a low-sloping sandy beach backed by a steeper cobble slope. During high wind conditions, wind can blow sand from the sandy beach into the cobble berm. Subsequent infilling of a dynamic revetment by aeolian (wind-driven) sand transport is hypothesized to affect its morphological development and performance, e.g. by reducing wave infiltration and increasing overtopping. However, aeolian sand transport on dynamic cobble berm revetments has not yet been measured or simulated with numerical models. Here, we use event-based field measurements to show that aeolian sediment transport on dynamic revetments is dependent on the wind speed and moisture content on the beach, and that dynamic revetments can trap 93–100 % of the aeolian sand transport from the beach. Additionally, we adapt a numerical aeolian sediment transport model (AeoLiS) to replicate the physical processes, such as sediment trapping, that alter sand transport on a dynamic revetment. As a result, the modified model reproduces the timing and spatial patterns of measured aeolian transport and the sand trapping efficiency of dynamic revetments. A simulation of sand infilling on a dynamic revetment shows how sand trapping is reduced once a dynamic revetment is filled with sand. The modified model considers wind-driven sand infilling and provides a pathway for considering the combined effect of marine and aeolian processes (i.e., by coupling with a hydrodynamic model) in dynamic revetment design.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"203 ","pages":"Article 104859"},"PeriodicalIF":4.5,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105826","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}
Coastal EngineeringPub Date : 2025-08-16DOI: 10.1016/j.coastaleng.2025.104856
Tharindu Manamperi , Alma Rahat , Doug Pender , Demetra Cristaudo , Rob Lamb , Harshinie Karunarathna
{"title":"Predicting shoreline changes using deep learning techniques with Bayesian optimisation","authors":"Tharindu Manamperi , Alma Rahat , Doug Pender , Demetra Cristaudo , Rob Lamb , Harshinie Karunarathna","doi":"10.1016/j.coastaleng.2025.104856","DOIUrl":"10.1016/j.coastaleng.2025.104856","url":null,"abstract":"<div><div>Accurate prediction of shoreline change is vital for effective coastal planning and management, especially under increasing climate variabilities. This study explores the applicability of deep learning (DL) techniques, particularly Long Short-Term Memory (LSTM) and Convolutional Neural Network-LSTM (CNN-LSTM) models, for shoreline forecasting at monthly to inter-annual timescales, under two modelling approaches—direct input (DI) and autoregressive (AR). All models demonstrated the ability to reproduce temporal shoreline variability, while the autoregressive DL models were performing better.</div><div>Further, a noise impact assessment revealed that seasonal decomposition and noise filtering significantly enhanced the model performance. In particular, the models using 52-week data decomposition and residual noise reduction improved the model performance. The reduction of data noises also resulted in narrower ensemble prediction envelopes, indicating that ensemble candidate models behave with low diversity. The temporal data resolution analysis showed that lower data resolutions reduce the predictive performance of the model and at least fortnightly data are required to satisfactorily capture the trend of variability of the shoreline position at this beach.</div><div>The use of ensemble predictions, derived from a selected subset of model trials based on their collective performance, proved beneficial by capturing diverse temporal behaviours, thereby offering a quasi-probabilistic forecast with minimal computational cost. Overall, the study underscores the potential of DL models, particularly with autoregressive architectures, for reliable and transferable shoreline change prediction. It also emphasizes the importance of data quality, resolution, and preprocessing in improving model robustness, laying the groundwork for future research into use of DL in multi-scale shoreline predictions.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"203 ","pages":"Article 104856"},"PeriodicalIF":4.5,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010581","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}
Coastal EngineeringPub Date : 2025-08-15DOI: 10.1016/j.coastaleng.2025.104854
S.P. Viaña-Borja , S. Heredia , G. Navarro , X. Santamarta-Benito , N. Araujo-Suarez , I. Caballero
{"title":"Comparative assessment of bathymetric methods using unmanned aerial vehicle (UAV) high-resolution multispectral imaging","authors":"S.P. Viaña-Borja , S. Heredia , G. Navarro , X. Santamarta-Benito , N. Araujo-Suarez , I. Caballero","doi":"10.1016/j.coastaleng.2025.104854","DOIUrl":"10.1016/j.coastaleng.2025.104854","url":null,"abstract":"<div><div>Unmanned Aerial Vehicles (UAVs) equipped with multispectral sensors offer a promising, cost-effective alternative for high-resolution bathymetric mapping in dynamic coastal environments. This study evaluates the feasibility of adapting two established satellite-derived bathymetric (SDB) methods, the Stumpf (S) and Caballero-Stumpf (CS), to UAV-based multispectral imagery (UDB, UAV-Derived Bathymetry). Four UAVs flights are conducted over Luarca (Northern Spain), capturing data from a port and an adjacent beach with varying turbidity and environmental conditions. Results indicates that the UDB<sub>green</sub> model, based on the green band reflectance, consistently outperforms in accuracy the UDB<sub>red</sub> model, based on the red band, with median absolute errors (MedAE) ranging from 0.41 to 0.67 m for depths up to 7 m. Conversely, UDB<sub>red</sub> exhibits poor performance in these waters. A composite methodology integrating multiple UAV flights is also tested through the first UAV-based implementation of the CS compositing method, originally developed for satellite imagery to address turbidity. However, it does not yield significant accuracy improvements over the traditional S model or single-image results, highlighting the influence of environmental factors and flight-specific parameters on UDB data quality. Given these findings, and considering that UAV platforms offer key operational advantages, such as higher spatial resolution, flexible acquisition timing, and better suitability for small or cloud-prone coastal areas, there is a strong need further validation of UAV-based techniques under varied coastal conditions.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"202 ","pages":"Article 104854"},"PeriodicalIF":4.5,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144878485","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}
Coastal EngineeringPub Date : 2025-08-12DOI: 10.1016/j.coastaleng.2025.104853
Weihan Li , Yi Pan , Weiqiu Chen , Giovanni Coco
{"title":"An initial analysis of swash flow velocity patterns","authors":"Weihan Li , Yi Pan , Weiqiu Chen , Giovanni Coco","doi":"10.1016/j.coastaleng.2025.104853","DOIUrl":"10.1016/j.coastaleng.2025.104853","url":null,"abstract":"<div><div>This study presents a comprehensive analysis of an extensive dataset comprising 63 time series of swash flow velocity extracted from 15 previous studies, including both laboratory experiments and field observations. A consistent pattern in the swash flow time series is identified across the beachface profile, characterized by an approximately linear decrease around the flow reversal point, followed by a deviation point and subsequent deceleration. By defining two key transitional times as functions of the relative location along the beachface, a general form of swash flow is established. The swash flow behavior during the early uprush and late backwash phases, the influencing factors affecting the characteristics of swash flow velocity time series, and the cross-shore distribution of initial uprush velocity are further discussed. Based on this analysis, a general representation of the temporal-spatial evolution of swash flow velocity is proposed. These findings provide new insights into swash hydrodynamics and offer a foundation for future quantitative parameterization of cross-shore swash flow processes.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"202 ","pages":"Article 104853"},"PeriodicalIF":4.5,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830436","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}
Coastal EngineeringPub Date : 2025-08-08DOI: 10.1016/j.coastaleng.2025.104823
Kaiqing Luo, Yiyong Dong, Jing Yuan
{"title":"Impact of mooring configurations on wave attenuation of porous floating breakwater: A comparative experimental study","authors":"Kaiqing Luo, Yiyong Dong, Jing Yuan","doi":"10.1016/j.coastaleng.2025.104823","DOIUrl":"10.1016/j.coastaleng.2025.104823","url":null,"abstract":"<div><div>Floating breakwaters are increasingly used for coastal protection, especially in deep-water environments where traditional fixed breakwaters are impractical. The performance of porous floating breakwaters (PFBs) is highly dependent on their mooring systems, which has not been thoroughly investigated to date. This study presents a comparative experimental investigation of four mooring systems, i.e., fixed, pile-restrained, catenary, and taut, for PFBs, focusing on their wave transmission coefficients (<span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub></math></span>) and motion response (heave, surge and pitch). The PFB, constructed from cubically packed stainless-steel spheres, was subjected to periodic waves with varying steepness and ratio of width (<span><math><mi>B</mi></math></span>) to wave length (<span><math><mi>L</mi></math></span>). Fixed mooring, with no dynamic response, provided good wave attenuation, especially when fully submerged (<span><math><mrow><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>≈</mo><mn>0</mn><mo>.</mo><mn>5</mn></mrow></math></span> for <span><math><mrow><mi>B</mi><mo>/</mo><mi>L</mi><mo>≥</mo><mn>0</mn><mo>.</mo><mn>18</mn></mrow></math></span>). Pile-restrained mooring, allowing vertical motion, performed comparably to emerged fixed mooring, with minimal impact from heave motion. Catenary mooring, characterized by high compliance, exhibited poor performance for long waves (<span><math><mrow><msub><mrow><mi>K</mi></mrow><mrow><mi>t</mi></mrow></msub><mo>></mo><mn>0</mn><mo>.</mo><mn>8</mn></mrow></math></span> for <span><math><mrow><mi>B</mi><mo>/</mo><mi>L</mi><mo><</mo><mn>0</mn><mo>.</mo><mn>3</mn></mrow></math></span>) due to large surge and heave motions. Taut mooring, with high stiffness due to pre-tensioned mooring chains, demonstrated superior attenuation when fully submerged, outperforming fixed mooring in some cases. However, its performance degraded when the PFB was not fully submerged and without the pre-tension. The study highlights the critical role of restricting translational motions (surge and heave) in enhancing wave dissipation. Submergence was also found to be a key factor, with fully submerged PFBs dissipating more energy. These findings provide valuable insights for optimizing mooring systems in practical applications.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"202 ","pages":"Article 104823"},"PeriodicalIF":4.5,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144860383","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}
Coastal EngineeringPub Date : 2025-08-08DOI: 10.1016/j.coastaleng.2025.104848
Giulia Bonanno , Giovanni Passalacqua , Claudio Iuppa , David R. Fuhrman , Carla Faraci
{"title":"Wave-induced incipient motion of non-buoyant plastic particles: Laboratory experiments","authors":"Giulia Bonanno , Giovanni Passalacqua , Claudio Iuppa , David R. Fuhrman , Carla Faraci","doi":"10.1016/j.coastaleng.2025.104848","DOIUrl":"10.1016/j.coastaleng.2025.104848","url":null,"abstract":"<div><div>The incipient motion of nine non-buoyant plastic particles, having different shapes and densities, beneath surface waves is systematically investigated on both smooth and rough beds in a 2D flume. In each test, ten identical particles are placed on the bed, and the threshold for motion is defined when at least half of the particles move during each wave cycle. Experimental results are first compared with the classical Shields curve, originally developed for natural sediments under steady flow. To enhance predictive accuracy, the present dataset was combined with additional data sets from the literature acquired under steady flows, and the consolidated data were subjected to a systematic analysis. As has been established for steady flows, the effects of static friction and hiding-exposure need to be accounted for. However, it is found that these alone are not sufficient to achieve reconciliation with the classical Shields diagram for parameterizing incipient motion conditions. To ensure consistency with classical formulations based on steady flows, the shear velocity near the bed was estimated under wave forcing by applying a phase-averaging method. The peak near-bed velocity during the wave crest phase was extracted and used to compute the corresponding friction velocity. The novelty of this study is that an additional function, depending on the ratio of boundary layer thickness to particle size, has been incorporated to parameterize incipient motion beneath unsteady (oscillatory) wave-induced flows to account for the partial submergence of particles within the boundary layer. After accounting for this additional dependence, reconciliation with the Shields diagram is achieved, with remaining scatters being of the same order of magnitude for all the considered datasets. The proposed framework improves predictions of plastic debris mobility under both steady and wave-driven flow conditions.</div></div>","PeriodicalId":50996,"journal":{"name":"Coastal Engineering","volume":"202 ","pages":"Article 104848"},"PeriodicalIF":4.5,"publicationDate":"2025-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827621","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}