Large-scale Wave Research Articles

Influence of seagrass meadow length on beach morphodynamics: An experimental study

A novel flume experiment was conducted to compare the sheltering effect of surrogate seagrass meadows of two different lengths against a bare beach (benchmark). The analyses focused on assessing the impact of meadow cross-shore extent on wave height attenuation, behaviour of wave orbital velocity components, sediment transport, and shoreline erosion. Throughout the tests conducted in the large-scale CIEM wave flume at LIM/UPC Barcelona, meadow density and submergence ratio remained constant, while irregular waves were run over an initial 1:15 sand beach profile. In both meadow layouts, a persistent decrease in wave height from the offshore area in front of the meadow to the breaking zone was found. This reduction was directly correlated with the length of the seagrass meadow. As a result of the reduction in wave energy, less erosion occurred at the shoreline in accordance with the decrease in wave height. The mean velocities exhibited changes in the velocity profile from the meadow area to the immediate zone behind the meadow, a phenomenon not observed in more onshoreward positions. Orbital velocities displayed a reduction exclusively for the long meadow case. This decrease was persistent up to the breaking zone. As a consequence of these changes, the long meadow layout led to a decrease in the volume of sediment transport and a breaker bar closer to the shoreline. The short meadow layout resulted in a higher volume of sediment transport compared to the long meadow layout, although still less than the benchmark layout. Furthermore, in the short meadow layout, the final bar was situated in a location similar to that observed in the benchmark layout.

The Stirring Tropics: Theory of Moisture Mode–Hadley Cell Interactions

Abstract Interactions between large-scale waves and the Hadley cell are examined using a linear two-layer model on an f plane. A linear meridional moisture gradient determines the strength of the idealized Hadley cell. The trade winds are in thermal wind balance with a weak temperature gradient (WTG). The mean meridional moisture gradient is unstable to synoptic-scale (horizontal scale of ∼1000 km) moisture modes that are advected westward by the trade winds, reminiscent of oceanic tropical depression–like waves. Meridional moisture advection causes the moisture modes to grow from “moisture-vortex instability” (MVI), resulting in a poleward eddy moisture flux that flattens the zonal-mean meridional moisture gradient, thereby weakening the Hadley cell. The amplification of waves at the expense of the zonal-mean meridional moisture gradient implies a downscale latent energy cascade. The eddy moisture flux is opposed by a regeneration of the meridional moisture gradient by the Hadley cell. These Hadley cell–moisture mode interactions are reminiscent of quasigeostrophic interactions, except that wave activity is due to column moisture variance rather than potential vorticity variance. The interactions can result in predator–prey cycles in moisture mode activity and Hadley cell strength that are akin to ITCZ breakdown. It is proposed that moisture modes are the tropical analog to midlatitude baroclinic waves. MVI is analogous to baroclinic instability, stirring latent energy in the same way that dry baroclinic eddies stir sensible heat. These results indicate that moisture modes stabilize the Hadley cell and may be as important as the latter in global energy transport. Significance Statement The tropics are characterized by steady circulations such as the Hadley cell as well as a menagerie of tropical weather systems. Despite progress in our understanding of both, little is known about how the mean circulations and the weather systems interact with one another. Here we show that tropical waves can grow by extracting moisture from the Hadley cell, thereby weakening it. They also transport moisture to higher latitudes. Our results challenge the notion that the Hadley cell is the sole transporter of energy out of the tropics and instead favor a view where tropical waves are also essential for the global energy balance. They dry the humid regions and moisten the drier regions via stirring.

Geometry-Dependent Elastic Flow Dynamics in Micropillar Arrays.

Regular device-scale DNA waves for high DNA concentrations and flow velocities have been shown to emerge in quadratic micropillar arrays with potentially strong relevance for a wide range of microfluidic applications. Hexagonal arrays constitute another geometry that is especially relevant for the microfluidic pulsed-field separation of DNA. Here, we report on the differences at the micro and macroscopic scales between the resulting wave patterns for these two regular array geometries and one disordered array geometry. In contrast to the large-scale regular waves visible in the quadratic array, in the hexagonal arrays, waves occur in a device-scale disordered zig-zag pattern with fluctuations on a much smaller scale. We connect the large-scale pattern to the microscopic flow and observe flow synchronization that switches between two directions for both the quadratic and hexagonal arrays. We show the importance of order using the disordered array, where steady-state stationary and highly fluctuating flow states persist in seemingly random locations across the array. We compare the flow dynamics of the arrays to that in a device with sparsely distributed pillars. Here, we observe similar vortex shedding, which is clearly observable in the quadratic and disordered arrays. However, the shedding of these vortices couples only in the flow direction and not laterally as in the dense, ordered arrays. We believe that our findings will contribute to the understanding of elastic flow dynamics in pillar arrays, helping us elucidate the fundamental principles of non-Newtonian fluid flow in complex environments as well as supporting applications in engineering involving e.g., transport, sorting, and mixing of complex fluids.

Risk Management of Coastal Ring Roads to Rate Abrasion on The Lhokseumawe City

This paper presents an approach for developing risk management strategies for ring roads in coastal abrasion Lhokseumawe ring roads. Currently, management strategies in these regions are designed to rubble mount breakwaters on coastal performance under traffic loads. However, recent large-scale waves and their associated damage to coastal areas have demonstrated the need to consider the height when making coastal management decisions. This paper aims to develop a risk management strategy that includes handling/controlling accelerated beach abrasion which damages coastal infrastructure buildings and the application of the ALARP scheme as an acceptable risk control limit for decision makers in risk management so as to minimize the potential impact at any given time... The methods consider the rate of coastal abrasion associated with hazards and the economic, social, and environmental consequences of collapse under high tide. The data were collected from the satellite Landsat range of the 1995-2021 year. The analysis adopted Digital Shoreline Analysis System with Enhanced Thematic Mapper (ETM). The risk management strategies are achieved by formulating and solving a multi-objective optimization problem. This problem's findings include abrasion -2.11 m/year and accretion maximum at 111.34 m or 4.45%. The height of the wave was found approximately range 2.33-10.25 sec, and the period average 4.57 m/year. In addition, the periods of the wave were in the range of 2.33-10.25 sec, and the average period was 4.57 sec. The topography characteristics were found between 0 and 8.60 meters, with an average level, is 4.30 meters. The percentage of the slope of the shoreline was found to be 2.90 to 4.47%, and the average beach slope was 3.76%. The risk management achieved in ring roads was relevant to the application scheme ALARP zone to solve the problem from very high to hight risk. The rubble mound breakwaters along the coast were believed to minimize abrasion and mitigate disasters to protect infrastructure ring roads for a long time.

Process-based classification of Mediterranean cyclones using potential vorticity

Abstract. Mediterranean cyclones (MCs) govern extreme weather events across the Euro-African Basin, affecting the lives of hundreds of millions. Despite many studies addressing MCs in the last few decades, their correct simulation and prediction remain a significant challenge to the present day, which may be attributed to the large variability among MCs. Past classifications of MCs are primarily based on geographical and/or seasonal separations; however, here we focus on cyclone genesis and deepening mechanisms. A variety of processes combine to govern MC genesis and evolution, including adiabatic and diabatic processes, topographic influences, land–sea contrasts, and local temperature anomalies. As each process bears a distinct signature on the potential vorticity (PV) field, a PV approach is used to distinguish among different “types” of MCs. Here, a combined cyclone-tracking algorithm is used to detect 3190 Mediterranean cyclone tracks in ECMWF ERA5 from 1979–2020. Cyclone-centered, upper-level isentropic PV structures in the peak time of each cyclone track are classified using a self-organizing map (SOM). The SOM analysis reveals nine classes of Mediterranean cyclones, with distinct Rossby-wave-breaking patterns, discernible in corresponding PV structures. Although classified by upper-level PV structures, each class shows different contributions of lower-tropospheric PV and flow structures down to the surface. Unique cyclone life cycle characteristics, associated hazards (precipitation, winds, and temperature anomalies), and long-term trends, as well as synoptic, thermal, dynamical, seasonal, and geographical features of each cyclone class, indicate dominant processes in their evolution. Among others, the classification reveals the importance of topographically induced Rossby wave breaking to the generation of the most extreme Mediterranean cyclones. These results enhance our understanding of MC predictability by linking the large-scale Rossby wave formations and life cycles to coherent classes of under-predicted cyclone aspects.

Aircraft observations in a tropical supercluster over the equatorial Indian Ocean during MISO-BOB field campaign

The Monsoon Intra-Seasonal Oscillations in the Bay of Bengal (MISO-BOB) field campaign was conducted in the Indian Ocean during the 2018 and 2019 summer monsoon seasons. WC-130J aircraft of the 53rd Weather Reconnaissance Squadron of the US Air Force participated in the campaign in June 2018. The dropsonde observations across a tropical supercluster showed zonal wind variations in association with the structure of the convectively coupled Kelvin wave (CCKW). Within the supercluster, easterlies (westerlies) were observed in the upper (lower) troposphere; this transformation occurred just below the 0∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{\\circ }$$\\end{document} C level. The cold pool had an easterly component throughout, and it was coldest (by 2.5∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{\\circ }$$\\end{document} C) at the center of the supercluster, deepest (∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document}1000m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1000\\,\\hbox {m}$$\\end{document}) at its rear/western end, and shallowest (∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 300 m) at the front/eastern end. The level of free convection (LFC) at the front end was at 897m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$897\\,\\hbox {m}$$\\end{document} altitude. At the eastern flank of the supercluster, zonal convergence in the lower troposphere occurred between 500-1500 m levels above the surface between the westerlies within the supercluster and opposing ambient easterlies. Thus, the uplifting of conditionally unstable air parcels above LFC to the east of the supercluster was likely to occur due to this convergence rather than the cold pool influence. Conversely, the western flank of the supercluster had low-level zonal divergence. These observations support the notion of ‘self-similarity’ among the mesoscale convective systems and large-scale waves.

Land Distribution in German and Mennonite Colonies During the NEP Period. Expectations and Reality

The article is devoted to the study of the relationship between the Soviet authorities and the German, as well as Mennonite communities, regarding land issues during the NEP period. It is based on the analysis of the official reports, memoirs and documents. The author studies the complex relationships between the central government, the regional level of authorities (provincial and district) and Mennonites. The land distribution in Mennonite colonies, as well as the cause and-effects of the process are analyzed. In the whirlwind of the internal and foreign political processes, the newly created Soviet state found itself on the edge of socio- economic conflicts. In order to solve urgent economic issues and curb mob violence, a number of economic reforms were adopted, which are known in history as the New Economic Policy. Most of the projects of the Soviet government were based on communist ideology at the initial stage. Those advanced farms’ lands, which used to belong to the Mennonites and Germans, were redistributed. Unemployed / recent employed people who had received some land, were not skilled and did not have a knack for agriculture. Therefore, they gradually abandoned their lands. That strategy undermined the land system and, as a result, became another pushing motivation for emigration and agricultural problems in the countryside. As a result of the Bolshevik government’s land program, the Mennonite community became embroiled in complex multilevel problems: a) intra- community land tensions caused by demographic processes and the resettlement of fellow refugees from starving regions of Soviet Russia to the colonies; b) conflicts with the population of neighboring villages and poor peasant committees, which often forced the issue of redistribution of Mennonite lands in their favor; c) failure of provincial and district executive committees to enforce resolutions of the supreme power to settle the land issue of the Mennonite community; d) ineffectiveness of the national minority committee; e) the perception by some Mennonites of new communist ideas – social equality. These reasons became important pushing factors for а large-scale wave of emigration of this ethno- confessional group to North America.

Data-driven scale identification in oscillatory dynamos

ABSTRACT Parker’s mean-field model includes two processes generating large-scale oscillatory dynamo waves: stretching of magnetic field lines by small-scale helical flows and by differential rotation. In this work, we investigate the capacity of data-driven modal analysis, dynamic mode decomposition (DMD), to identify coherent magnetic field structures of this model. In its canonical form, the only existing field scale corresponds to the dynamo instability. To take into account multiscale nature of the dynamo, the model was augmented with coherent in time flow field, forcing small-scale magnetic field with a faster temporal evolution. Two clusters of DMD modes were obtained: the ‘slow’ cluster, located near the dynamo wave frequency and associated with its non-linear self-interaction, and the ‘fast’ cluster, centred around the forcing frequency and resulting from the interaction between the wave and the flow. Compared to other widely used methods of data analysis, such as Fourier transform, DMD provides a natural spatiotemporal basis for the dynamo, related to its non-linear dynamics. We assess how the parameters of the DMD model, rank, and delay, influence its accuracy, and finally discuss the limitations of this approach when applied to randomly forced, more complex dynamo flows.

Assessing the Effect of Chest Orientation on Pulmonary Pressure Under Free Field Shock Waves: A Numerical Analysis

Purpose This study explores how thoracic orientation affects lung pressure and injury outcomes from shock waves, building on earlier research that suggested human posture impacts injury severity. Methods A layered finite element model of the chest was constructed based on the Chinese Visual Human Dataset (CVH), which includes the rib layer and intercostal muscle layer. The dynamic response of the chest under 12 different angles oriented shock waves under incident pressures of 200kPa and 500kPa was calculated. The correspondence between lung pressure at different angles, chest wall motion velocity and lung stress, and differences in pressure/stress of lung tissue behind ribs and intercostal muscle were analyzed. Results The dynamic response of the chest can be roughly divided into four processes. High local intrapulmonary pressure areas were primarily in the anterior lobe margin and lung's central region. A 500kPa incident wave at 0° could cause slight lung injury, whereas at 240°, the pressure was non-harmful. Lung tissue pressure and stress induced by chest wall movement were significantly higher behind the intercostal muscles than behind the ribs, with a difference of about 2-3 times. Conclusions This layered model provides a cost-effective tool for large-scale shock wave impact simulations on the chest. Chest wall movement velocity strongly correlates with lung stress distribution. The significant density and sound velocity differences among ribs, intercostal muscles, and lungs cause an acoustic impedance mismatch, leading to “striped bleeding” marks in post-impact lungs. This research enhances understanding of chest and lung injury mechanisms and informs the development of protective measures.

Hydrodynamic coupling of multi-fidelity solvers in REEF3D with application to ship-induced wave modelling

Ship-induced waves are an increasingly relevant hydrodynamic forcing factor in waterways travelled by large seagoing ships. The discrepancy between the small-scale wave-structure interaction near embankments and the larger-scale wave generation and propagation poses challenges for the prediction of ship-induced waves as a multi-scale problem. Therefore, a novel hydrodynamic coupling interface is presented that allows information transfer from the shallow-water-equation (SWE) solver REEF3D::SFLOW to the 3D-RANS-solver REEF3D::CFD. The implementation consists of a one-way coupling, where the solution from the SWE solver is imposed to one or multiple relaxation zones of the CFD solver. A series of verification cases shows that the implementation of the interface is accurate and only small deviations are introduced due to the 2D-3D dimensional mismatch of the numerical models involved. An application is presented, showing how the coupled SWE-CFD model can be employed to study ship-induced groin overtopping.

From Internal Waves to Turbulence in a Stably Stratified Fluid.

We report on the statistical analysis of stratified turbulence forced by large-scale waves. The setup mimics some features of the tidal forcing of turbulence in the ocean interior at submesoscales. Our experiments are performed in the large-scale Coriolis facility in Grenoble which is 13m in diameter and 1m deep. Four wave makers excite large-scale waves of moderate amplitude. In addition to weak internal wave turbulence at large scales, we observe strongly nonlinear waves, the breaking of which triggers intermittently strong turbulence at small scales. A transition to strongly nonlinear turbulence is observed at smaller scales. Our measurements are reminiscent of oceanic observations. Despite similarities with the empirical Garrett and Munk spectrum that assumes weak wave turbulence, our observed energy spectra are rather to be attributed to strongly nonlinear internal waves.

Oceanic eddies induce a rapid formation of an internal wave continuum

Oceanic internal waves are a major driver for turbulent mixing in the ocean, which controls the global overturning circulation and the oceanic heat and carbon transport. Internal waves are observed to have a continuous energy distribution across all wave frequencies and scales, commonly known as the internal wave continuum, despite being forced at near-inertial and tidal frequencies at large scales. This internal wave continuum is widely thought to be developed primarily through wave-wave interactions. Here we show, using realistic numerical simulations in the subpolar North Atlantic, that oceanic eddies rapidly distribute large-scale wind-forced near-inertial wave energy across spatio-temporal scales, thereby forming an internal wave continuum within three weeks. As a result, wave energy dissipation patterns are controlled by eddies and are substantially enhanced below the mixed layer. The efficiency of this process potentially explains why a phase lag between high-frequency and near-inertial wave energy was observed in eddy-poor regions but not in eddy-rich regions. Our findings highlight the importance of eddies in forming an internal wave continuum and in controlling upper ocean mixing patterns.

Microwave Radar Sensing of Sea Waves: An Effective Reflection Coefficient

At the small incidence angles, the dominant backscattering mechanism for sea waves is the quasi-specular backscattering mechanism. The power of the reflected signal depends on the distribution function of the slopes of large-scale waves (in comparison with radar wavelength) and on the effective reflection coefficient, which is introduced instead of the Fresnel coefficient. In this paper, we discussed a new method for calculating the effective reflection coefficient from the wave scatterometer SWIM data. For the first time, measurements are performed by a radar at different azimuth angles at small incidence angles. This makes it possible to measure the effective reflection coefficient. An original algorithm was developed for data processing and determination of the total mean square slopes of large-scale sea waves and the azimuth dependence of the backscattering radar cross section at zero incidence angle. In the result of subsequent processing, the azimuth dependence of the effective reflection coefficient is retrieved. SWIM data were used to evaluate the developed algorithm. Processing of the test data set confirmed the efficiency of the algorithm. The azimuth anisotropy coefficients for the mean square slopes of large-scale waves and the effective reflection coefficient are calculated

Changes in the parameters of extreme temperature events in the western part of the Russian Arctic according to ERA5 and MERRA-2 reanalyses in 1980–2022

The air temperature in the Arctic zone of Russia is increasing at a rate of 0.71 °C per decade, which is three times faster than the global average. The warming of climate is accompanied by an increase in its extremeness, which leads to an increase in the number of dangerous hydrometeorological phenomena. The most significant changes occurred in the statistics of large-scale summer heat waves in European Russia. One of the most important goals in studying current climate changes is to study the frequency of extreme hydrometeorological phenomena, in particular, heat or cold waves. In this paper, we investigate the average daily anomalies relative to the annual variation of air temperature at a height of 2 meters from the surface in the region of the western part of the Russian Arctic (60°–75° N, 30°–85° E), according to ERA5 and MERRA-2 atmospheric reanalyses for the period 1980–2022. Their root-mean-square deviations and the distribution of their average number per year are calculated. We have plotted the fields of average values and the rate of changes in the amplitude, duration and number of anomalous temperature events which exceed two standard deviations in the study region. Areas of increase and decrease in the amplitude, duration and number of extreme events, both with positive and negative temperature anomalies, are displayed. In general, it can be concluded that, on average, the amplitudes of positive extreme air temperature anomalies in the study area slightly increase. The duration of positive extreme anomalies is growing everywhere at a rate of 0.2 days per 10 years. The duration of negative extreme anomalies slightly decreases. The number of events with negative extreme anomalies has been decreasing at a rate of –0.5 to –3 events per year for 10 years, while the number of events with positive extreme anomalies has been increasing from 0.1 to 1 events per year for 10 years.The results obtained significantly expand our knowledge of the spatiotemporal features of the ongoing changes in the extreme climate of the western part of the Russian Arctic, which is of paramount importance for the analysis and forecasting of the development of natural and socio-economic systems in the region under study.

Spatio-temporal ocean wave conditions forecasting using MA-TrajGRU model in the South China sea

Waves are an oceanic phenomenon that involve intricate mechanisms of generation and dynamic processes. In the past, wave forecasting mainly primarily depended on complicated numerical models; however, these models are computationally expensive and time-consuming. As a result, different deep learning techniques have been tested. In the South China Sea, the generation and propagation of ocean waves are impacted by many factors, which are affected including the swell and typhoon as well as complex topography, making most of the deep learning methods limited in their accuracy. To address this issue, a Spatio-temporal network integrating multivariate attention mechanisms, MA-TrajGRU, is introduced and applied to forecast the ocean wave conditions during the typhoon process in the South China Sea. We simulated wave data for 2017–2021 using SWAN and validated it against buoy observations. The forecast data includes significant wave height (Hs) and mean wave period (Tm) with a spatial resolution of 0.1° and a temporal resolution of 1 h. Wave forecasting experiments were performed 24 h in advance to evaluate MA-TrajGRU. The errors of MA-ConvLSTM and MA-TrajGRU with the multivariate attention mechanism addition are lower with MAE of 0.136 m, MSE of 0.0582 m2, and PCC of 0.9555 for Hs; MAE of 0.2352 s, MSE of 0.1393 s2, and PCC of 0.9708 for Tm. We conducted experiments on wave forecasting during typhoon processes and observed that MA-TrajGRU performs much better than commonly used Spatio-temporal network models. Thus, MA-TrajGRU can forecast the spatial and temporal distribution of large-scale ocean waves in the South China Sea, especially during typhoons. Therefore, it has great potential for disaster prevention and mitigation in marine engineering.

Two-dimensional inverse energy cascade in a laboratory surf zone for varying wave directional spread

Surfzone eddies enhance the dispersion and transport of contaminants, bacteria, and larvae across the nearshore, altering coastal water quality and ecosystem health. During directionally spread wave conditions, vertical vortices (horizontal eddies) are injected near the ends of breaking crests. Energy associated with these eddies may be transferred to larger-scale, low-frequency rotational motions through an inverse energy cascade, consistent with two-dimensional turbulence. However, our understanding of the relationships between the wave conditions and the dynamics and energetics of low-frequency surfzone eddies are largely based on numerical modeling. Here, we test these relationships with remotely sensed and in situ observations from large-scale directional wave basin experiments with varying wave conditions over alongshore-uniform barred bathymetry. Surface velocities derived with particle image velocimetry were employed to assess the spatial scales of low-frequency surfzone eddies and compute structure functions with alongshore velocities. Second-order structure functions for directionally spread waves (σθ≥10°) are consistent with energy flux to larger or smaller length scales, while normally incident, unidirectional waves do not display this behavior. Third-order structure functions suggest that the surfzone flows exhibit a bidirectional energy cascade—a direct cascade to smaller and inverse cascade to larger length scales—during large directional spreads waves (σθ≥18°). However, there is not decisive evidence of an inverse energy cascade for moderate directional spreads (σθ=10°). Energy flux varies by cross-shore location and increases with increasing directional spread and wave height. Eddy decorrelation length scales weakly depend on wave directional spread. These findings advance our understanding of the dynamics linking wave breaking to large-scale rotational motions that enhance mixing and lead to rip currents, important conduits for cross-shore material exchange.

Influence of Beach Slope on Morphological Changes and Sediment Transport under Irregular Waves

This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves.

Propagation of generalized Korteweg-de Vries solitons along large-scale waves.

We consider propagation of solitons along large-scale background waves in the generalized Korteweg-de Vries (gKdV) equationtheory when the width of the soliton is much smaller than the characteristic size of the background wave. Due to this difference in scales, the soliton's motion does not affect the dispersionless evolution of the background wave. We obtained the Hamilton equationsfor soliton's motion and derived simple relationships which express the soliton's velocity in terms of a local value of the background wave. Solitons' paths obtained by integration of these relationships agree very well with the exact numerical solutions of the gKdV equation.

Establishment and validation of a viscous-potential coupled and graphics processing unit accelerated numerical tank based on smoothed particle hydrodynamics and high-order spectral methods

The smoothed particle hydrodynamics (SPH) method is an entirely Lagrangian and truly meshless numerical tool that is inherently suitable for simulating violent viscous free-surface flows, whilst it usually renders considerable simulation time when solving large-scale engineering problems. The high-order spectral (HOS) method is an accurate and very efficient numerical tool for modeling a large-scale inviscid gravity wave field, whilst it is hard to tackle complex physical phenomena due to the dependence on the potential flow theory. This paper aims to propose a viscous-potential coupled and graphics processing unit accelerated numerical model for establishing a high-fidelity and high-efficiency numerical wave tank. In this coupling scheme, the SPH method is applied in the near-field where violent physical processes exist to accurately capture complex free-surface behaviors such as overturning and breaking, whilst the HOS method is applied in the far-field where the water undergoes gentle motion to efficiently generate a desired gravity wave. A dedicated SPH–HOS coupling interface is also presented to accurately transmit the flow information from the HOS side to the SPH side. Meanwhile, an SPH–HOS buffer region with several key techniques is also proposed to ensure a successful coupling between the two numerical methods. Different benchmarks demonstrate that the present SPH–HOS coupling method absorbs the respective advantages of the two numerical methods and shows great feasibility and reliability in solving hydrodynamic problems involving gravity wave generation, propagation, deformation, and its interaction with marine structures.

Two-dimensional simulations of large-scale violent breaking wave impacts on a flexible wall

Two-dimensional simulations of large-scale violent breaking wave impacts on a flexible wall