Effects Of Wave Breaking Research Articles

Effects of wave breaking on moisture flux

Wave breaking is a ubiquitous phenomenon in ocean dynamics, serving as a critical conduit for the exchange of momentum, heat, and energy between the atmosphere and the ocean. Although its vital role in air-sea moisture exchange is widely acknowledged, quantifying its exact impact on moisture flux remained quite challenging due to data limitations and the inherently turbulent nature of the process. To overcome these challenges, we construct a comprehensive 10-year global dataset that incorporates multiple breaking wave variables, informed by statistical breaking theories, to capture the intricacies of the breaking process and its consequential effects. We then employ a stacked machine learning model to elucidate the complex relationships between wave breaking and moisture flux. The performance of our stacked model, which is enriched with breaking wave variables, is validated against the fifth-generation European Centre for Medium-Range Weather Forecasts reanalysis data (ERA5). The results offer excellent predictions and highlight the importance of breaking-wave-related variables in regulating moisture flux, thereby substantiating the integral role of wave breaking in modulating air-sea interactions and moisture transport.

A Major Improvement of Atmospheric Wave Boundary Layer Model for Storm Surge Modeling by Including Effect of Wave Breaking on Air–Sea Momentum Exchange

Abstract Accurate estimation of the wind stress under extreme conditions is crucial for modeling storm surges and storm waves, which is important to the development of a warning system for coastal disaster prevention. The problem, however, is highly challenging owing to the presence of complex ocean surface processes under the action of unusually strong wind. In this study, the existing atmospheric wave boundary layer model is significantly enhanced by including various effects of wave breaking. Both the effect of wave breaking on the dissipation of energy and its effect on the transfer of momentum within the atmospheric boundary layer are carefully formulated. The wind stress coefficients obtained with the enhanced model are shown to be in good agreement with the measurements in not only deep but also shallow waters. The enhanced atmospheric wave boundary layer model is coupled with ocean wave as well as circulation models to simulate typhoon-induced storm surges and storm waves in the Pearl River delta region. The computational results show that the coupled model with improved evaluation of the wind stress is substantially advantageous when compared with existing approaches.

Experimental Testing on Tuned Liquid Dampers for Implementation in Industrial Chimneys.

A TLD is a passive damping device that works by dissipating energy through the sloshing of the liquid and the effect of wave breaking, thereby controlling the vibrations of the structure. One of the applications where TLDs are of great interest is in the case of industrial chimneys since these structures often have a very low natural frequency, which can be easily achieved in a control device of this type. The main objective of this study is to evaluate the behaviour of an annular TLD composed of multiple cells through laboratory tests and investigate if it is adequate to design it as an agglomeration of smaller rectangular TLDs. The influence of the amplitude of displacement on the behaviour of the annular TLD will also be analysed. The tests were performed on a shaking table and recurring with pendulums of the same length but of different masses. Three reservoirs were studied as TLDs: a rectangular one, a cell of an annular TLD and a quarter-ring of an annular TLD. This study concluded that the analytical methods developed in previous studies were, in general, adequate for the design of a rectangular TLD and that it was reasonable to design the annular TLD studied as a combination of rectangular ones, as its cells were a close match to a rectangle of similar dimensions. It was also concluded that a compartmentalised annular TLD is an adequate solution for the vibration control of structures with high displacements.

Multiscale dynamics of transient merging between western disturbances and monsoonal lows: Connections to the July 2023 flood in Himachal Pradesh

The Himachal Pradesh region experienced an unprecedented 436% more rainfall than normal from July 7th to 10th, 2023, resulting in devastating landslides, flash floods, and significant socio-economic losses. Using rainfall observations and reanalysis data, this study investigates the dynamics of the extreme precipitation event that caused the disastrous 2023 flood in Himachal Pradesh, India. Prior to the flood, moderate rainfall events saturated the mountainsides, making them more vulnerable to landslides and flash floods. Local features such as rapid convergence, vertical velocity, relative humidity, relative vorticity, and moisture flux accumulation were observed to decrease following the extreme precipitation event, indicating a short-duration cloud burst event. Further, the study reveals a large-scale circulation pattern linking the extratropic and monsoonal low, which is favorable for extreme precipitation in the Himachal Pradesh region. This pattern includes a transient merging of eastward-propagating trough in the mid-upper-level, which extends southward and a monsoon low moving westward across India. The key elements of this transient merging feature consist of a Rossby wave train structure and a blocking high west of the features. The Rossby wave breaking effect occurred downstream of the blocking high two days prior to extreme precipitation event occurrence. This allowed high potential vorticity stratospheric air to intrude the equator and troposphere, causing surface pressure change and enhanced vertical motion, thereby advecting high amount of moisture causing extreme precipitation leading to catastrophic floods. Overall, the findings of this study hold direct implications for early warning systems and disaster preparedness in the face of extreme precipitation-induced flood situations triggered by such transient merging features.

Effects of solitary wave breaking on the hydrodynamic performance of a submerged horizontal plate: A physical modeling study

A series of physical model tests were conducted to investigate the solitary wave control performance of a submerged horizontal plate (SHP). Hydrodynamic coefficients were analyzed for a wide range of SHP specifications, placement conditions, and dimensionless factors. Three wave breaking types on the SHP were identified: non-breaking, collapsing breaker, and plunging breaker. Their correlation with modified wave breaking classification parameters and dimensionless factors was investigated. Indirect reflected waves resulting from backflow were found to take precedence over direct reflected waves generated by the fluid resistance of the SHP. The dissipation coefficient increased as the friction and shoaling effects of the SHP, along with the nonlinearity of the solitary wave, grew more pronounced. The indirect reflection coefficient and the transmission coefficient exhibited an inverse relationship. The reflection coefficient achieved its peak value, while the transmission coefficient attained its minimum value within specific ranges. Based on the modified parameters, the hydrodynamic coefficients exhibited similar distributions. The modified surf-similarity parameter was found to be more suitable for classifying wave breaking types and predicting dissipation coefficients than the other two parameters. These experimental results can be utilized as foundational data for the optimal design of SHPs in controlling solitary waves.

Analysis of wave breaking on synthetic aperture radar at C-band during tropical cyclones

ABSTRACT The purpose of our work is to analyze the effect of wave breaking on dual-polarized (vertical-vertical (VV) and vertical-horizontal (VH)) synthetic aperture radar (SAR) image in the C-band during tropical cyclones (TCs) based on the machine learning method. In this study, more than 1300 Sentinel-1 (S-1) interferometric-wide (IW) and extra wide (EW) mode SAR images are collocated with wave simulations from the WAVEWATCH-III (WW3) model during 400 TCs. The validation of the significant wave height (SWH) simulated using the WW3 model against Jason-2 altimeter data. The winds for S-1 SAR images are reconstructed using wind retrievals in VV and VH polarization. The non-polarized (NP) contribution σ wb caused by wave breaking is assumed to be the result of the SAR-measured normalized radar cross-section (NRCS) σ 0 minus the Bragg resonant roughness σ br without the distortion of rain cells during TCs. The σ br is simulated by imputing wave spectra from the WW3 model into the theoretical backscattering model. It is found that the ratio (σ wb /σ 0) in VV polarization is related to the wind speed, the wind direction relative with the flight orientation, and radar incidence angle. Following this rationale, the Adaptive Boosting (AdaBoost) model was used for the estimation of NP contribution σ wb during TCs and are implemented for more than 300 dual-polarized S-1 images to validate the model. It is found that for the comparison between the sum of simulation NRCS and SAR observations, the root mean squared error (RMSE) is 1.95 dB and the coefficient (COR) is 0.86, which is better than a 2.83 dB RMSE and a 0.67 COR by empirical model. It is concluded that the AdaBoost model has a good performance on NP component simulation during TCs.

Experimental investigation into the effects of strong winds on the transport of overtopping water mass over a vertical seawall

ABSTRACT Hydraulic experiments using a wave flume with a wind tunnel at a scale of 1/40 were carried out to investigate the effect of wind on wave overtopping of a vertical seawall. To ascertain the possible effects of wave breaking, incident waves with various wave steepness (0.0102 to 0.0371) and three kinds of wind forcing (0 m/s, 6.84 m/s, 10.04 m/s) were used. The authors found that winds significantly increased the overtopping rate in general, and that there is a clear relationship between the overtopping rate and the wave steepness. Velocity fields obtained from PIV analysis revealed that the onshore winds directly enhanced the transport of overtopping water mass. The influence of the wind on the wave hydrodynamic processes that indirectly have an effect on the overtopping rate (such as the formation of a partially standing wave, breaker location, and breaker type) is also discussed. The perspective of treating wave overtopping as a transport of water mass could provide a novel understanding of complex fluid behavior, which would help to formulate countermeasures against future disasters influenced by intensive wind forcing.

Bifurcation analysis, chaotic analysis and diverse optical soliton solutions of time-fractional (2+1) dimensional generalized Camassa-Holm Kadomtsev-Petviashvili equation arising in shallow water waves

This paper presents a study on (2+1) generalized Camassa-Holm Kadomtsev-Petviashvili equation, which is used to describe the behavior of shallow water waves in nonlinear media. The considered equation provides a more accurate description of wave behavior compared to linear wave equations and can account for wave breaking and other nonlinear effects. This model can be used to describe and study the behavior of nonlinear waves such as rogue waves in complex fluid dynamics scenarios. This includes the behavior of waves in stratified fluids, nonlinear dispersive media and wave interactions in fluid flows with varying velocities and densities. The bifurcation analysis of the governing equation has been performed using the planar dynamical system method. The chaotic behavior of the dynamical system has been examined by utilizing various techniques such as time series analysis and the construction of 2D and 3D phase space trajectories. Furthermore, the introduction of a perturbed term has resulted in the observation of chaotic and quasi-periodic behaviors across a range of parameter values. The considered equation has been reduced to ordinary differential equation by performing symmetry reduction. The Kudryashov method has been used to obtain the exact solution of reduced equation. The single soliton solution of governed equation has been obtained by using Hirota method and impact of fractional parameter on the obtained solution has been studied using graphical representation. The extended sinh-Gordon equation expansion method and modified generalized exponential rational function method have been exploited to obtain dark, bright and singular soliton solutions of considered equation. The motivation for this study arises from the need to understand and analyze the complex dynamics of shallow water waves in nonlinear media with a particular focus on the (2+1) generalized Camassa-Holm Kadomtsev-Petviashvili equation. By performing symmetry reduction and applying various analytical methods, we aim to unravel the intricate behavior and soliton solutions of considered equation, contributing to the broader understanding of nonlinear wave phenomena.

Wave retrieval from quad-polarized Chinese Gaofen-3 SAR image using an improved tilt modulation transfer function

ABSTRACT An accurate Modulation Transfer Function (MTF) is essential for Synthetic Aperture Radar (SAR) wave spectra retrieval. This study aimed to investigate the performance of a quad-polarized wave retrieval algorithm based on fully polarimetric SAR image data using the improved tilt MTF and considering the influence of wind speed. The tilt MTF is the key factor in the wave retrieval scheme from quad-polarized (Vertical–Vertical (VV), Horizontal–Horizontal (HH), Vertical–Horizontal (VH), and Horizontal–Vertical (HV)) SAR images. In this study, the waves were inverted from more than 1300 Gaofen-3 (GF-3) images acquired in quad-polarization strip mode with a spatial resolution of 16 m and a swath coverage of 50 km. The winds were retrieved using the Geophysical Model Function (GMF) C-band SAR model for Gaofen-3 (CSARMOD-GF), which is suitable for re-calibrated GF-3 images in VV-polarization. The comparison of the wind speed yielded a Root Mean Square Error (RMSE) of 1.73 m/s and a Correlation Coefficient (COR) of 0.94. The validation of the Significant Wave Height (SWH) simulated using the Waves Nearshore (SWAN) model against Haiyang-2B (HY-2B) altimeter data yielded an RMSE of 0.56 m and a COR of 0.87. The results reveal that the SAR-derived wind and SWAN-simulated SWH are suitable for analysis of SAR wave retrieval. The full polarimetric technique was applied to the collected images, and the statistical analysis yielded a RMSE of 0.51 m, a COR of 0.75, and a Scatter Index (SI) of 0.44 compared with the SWHs retrieved using the simulations from the SWAN model. The non-polarized contribution in the Normalized Radar Cross Section (NRCS; unit: dB) caused by wave breaking was calculated using a theoretical approach that employs the VV-polarized calibrated NRCS and HH-polarized calibrated NRCS. The effect of wave breaking on the SAR retrieval waves was studied. The bias (SAR-derived minus SWAN-simulated SWH) increased as the (/) ratio (>0.4) increased, and the accuracy improved when the ratio was less than 0.4. This behavior is reasonable since the wave breaking inevitably affects the tilt modulation. Therefore, wave breaking should be considered in SAR wave retrieval using the approach proposed in this paper under extreme sea states, such as typhoons and hurricanes.

Enhanced ocean wave modeling by including effect of breaking under both deep- and shallow-water conditions

Abstract. Accurate description of the wind energy input into ocean waves is crucial to ocean wave modeling and a physics-based consideration on the effect of wave breaking is absolutely necessary to obtain such an accurate description. This study evaluates the performance of an improved formula recently proposed by Xu and Yu (2020), who took into account not only the effect of breaking but also the effect of airflow separation on the leeside of steep wave crests in a reasonably consistent way. Numerical results are obtained through coupling an enhanced atmospheric wave boundary layer model with the ocean wave model WAVEWATCH III (v5.16). The coupled model has been extended to be valid in both deep and shallow waters. Duration-limited waves under controlled normal conditions and storm waves under practical hurricane conditions are studied in detail to verify the improved model. Both the representative wave parameters and the parameters characterizing the wave spectrum are discussed. It is shown that the improved source-term package for the wind energy input and the wave energy dissipation leads to more accurate results under all conditions. It performs evidently better than other standard source-term options of ST2, ST4 and ST6 embedded in WAVEWATCH III. It is also demonstrated that the improvement is particularly important for waves at their early development stage and waves in shallow waters.

Langmuir Turbulence Controls on Observed Diurnal Warm Layer Depths

AbstractThe turbulent ocean surface boundary layer (OSBL) shoals during daytime solar surface heating, developing a diurnal warm layer (DWL). The DWL significantly influences OSBL dynamics by trapping momentum and heat in a shallow near‐surface layer. Therefore, DWL depth is critical for understanding OSBL transport and ocean‐atmosphere coupling. A great challenge for determining DWL depth is considering wave‐driven Langmuir turbulence (LT), which increases vertical transport. This study investigates observations with moderate wind speeds (4–7 m/s at 10 m height) and swell waves for which breaking wave effects are less pronounced. By employing turbulence‐resolving large eddy simulation experiments that cover observed wind, wave, and heating conditions based on the wave‐averaged Craik‐Lebovich equation, we develop a DWL depth scaling unifying previous approaches. This scaling closely agrees with observed DWL depths from a year‐long mooring deployment in the subtropical North Atlantic, demonstrating the critical role of LT in determining DWL depth and OSBL dynamics.

A new crest height distribution for nonlinear and breaking waves in varying water depths

The statistical distribution of zero-crossing crest heights represents a critical design input for a wide range of engineering applications. The present paper describes the development and validation of a new crest height model, suitable for application across a broad range of water depths. The purpose of this model is two-fold: first, to describe the amplifications of the largest crest heights arising due to nonlinear interactions beyond a second-order of wave steepness, and second, to incorporate the dissipative effects of wave breaking. Although these two effects act counter to each other, there is substantial evidence to suggest departures from existing models based upon weakly nonlinear second-order theory; the latter corresponding to current design practice. The proposed model has been developed on the basis of a significant collection of experimental results and a small subset of field measurements. It incorporates effects arising at different orders of nonlinearity as well as wave breaking in a compact formulation and covers a wide range of met-ocean conditions. Importantly, the new model has been independently validated against a very extensive database of experimental and field measurements. Taken together, these include effective water depths ranging from shallow water (kpd≈0.5) to deep water (kpd>3) and sea-state steepnesses covering mild, severe and extreme conditions. The new model is shown to provide a significant improvement in crest height predictions over existing methods. This is particularly evident in the steepest, most severe sea-states which inevitably form the basis of design calculations.

Intense high-harmonic optical vortices generated from a microplasma waveguide irradiated by a circularly polarized laser pulse

A scheme for generating intense high-harmonic optical vortices is proposed. It relies on spin-orbit interaction of light when a relativistically strong circularly polarized laser pulse irradiates a microplasma waveguide. The intense laser field drives a strong surface wave at the inner boundary of the waveguide, which leads to high-order-harmonic generation as the laser is traveling inside. For a circularly polarized drive laser, the optical chirality is imprinted to the surface wave, which facilitates conversion of the spin angular momentum of the fundamental light into orbital angular momenta of the harmonics. A ``shaken waveguide'' model is developed showing that the aforementioned phenomenon arises due to a nonlinear plasma response that modifies the electromagnetic mode at high intensities. We further show that the phase velocities of all the harmonic beams are automatically matched to the driving laser, so that the harmonic intensities increase with propagation distance. The efficiency of harmonic production is related to the surface wave breaking effect, which can be significantly enhanced using a tightly focused laser. Our simulation suggests that an overall conversion efficiency of $\ensuremath{\sim}5%$ can be achieved.

A Numerical Investigation of the Effect of Wave‐Induced Mixing on Tropical Cyclones Using a Coupled Ocean‐Atmosphere‐Wave Model

AbstractOcean surface waves play a significant role in regulating the sea surface temperature and mixed layer depth, which are essential for accurate prediction of tropical cyclone (TC) intensity. The effects of wave breaking and wave orbital motion induced mixing on the TC intensity and size are investigated using a coupled ocean‐atmosphere‐wave model for both idealized and real TC cases. The results show that both wave breaking and wave orbital motion lead to greater sea surface temperature cooling and mixed layer deepening, resulting in decreases in TC intensity and size owing to the reduction of air‐sea heat fluxes. Wave orbital motion has a slightly greater effect than wave breaking on the TC intensity and size when the mixed layer is shallow, whereas it has a much greater effect when the mixed layer is deep. In addition, including wave orbital motion induced mixing in models can effectively reduce the error in simulated TC size.

An experimental study on added resistance focused on the effects of bow wave breaking and relative wave measurements

The added resistance is a resistance component that is not yet satisfactorily predicted, although its accurate estimation is crucial – both from an environmental and economic point of view – from the design stage of a ship until its operation. One of the possible sources of overprediction is the occurrence of bow wave breaking. The first aim of this paper is to study the effect of bow wave breaking on added resistance by combining visual observations with resistance tests. On the other hand, as the bow region of a ship appears to be the most dominant contributor to added resistance, this paper introduces a dynamic waterline detection method involving stereo vision. This experimental method is applied to reach the second aim of this paper, which is to stress the importance of the relative wave elevation in the bow region of the ship. By placing stereo rigs inside the hull of a semi-transparent ship, the waterline at each momnent in time can be tracked using an edge detection algorithm. By performing resistance tests on the Delft Systematic Deadrise Series ship model no. 523, the added resistance is observed to be proportional to the relative wave height squared. The data of the experiment and the information necessary to reproduce the experiment are shared through https://doi.org/10.4121/19525852.

Step approximation on oblique water wave scattering and breaking by variable porous breakwaters over uneven bottoms

In this study, the scattering of oblique water surface gravity waves by variable porous breakwaters over uneven bottoms is investigated using the eigenfunction matching method (EMM). In the EMM procedure, the variable breakwaters and bottom profiles were sliced into shelves separated by steps. The solutions on the shelves are composed of eigenfunctions. Then, by applying the conservations of mass and momentum, a system of linear equations is obtained and can be solved with a sparse-matrix solver. The effects of wave breaking and dissipation were also included in the EMM formulation using energy-dissipation factors. In order to validate the proposed EMM method, the numerical solutions were compared with the results in the literatures for non-breaking wave scattering by rectangular and parabolic porous breakwaters. The convergence of the proposed solutions was studied. Then some discussions were provided when the EMM with energy-dissipation factors was applied to evaluate the surface elevations of breaking and/or dissipated waves. The numerical results illustrated the potential application of the EMM for problems with wave breaking and dissipation if the empirical formulas for the energy-dissipation factors can be well calibrated in future researches. Some further applications were provided, including wave scattering by multiple porous breakwaters.

Non‐Local Energy Dissipation of Lee Waves and Turbulence in the South China Sea

AbstractBreaking of internal lee waves has been shown to drive enhanced turbulence and mixing in regions where strong bottom flows interact with rough topography. However, theoretical predictions for the energy conversion from the bottom flows into lee waves differ from the corresponding turbulent energy dissipation rates observed locally at the wave generation sites. Recent idealized numerical simulations suggest that the discrepancy may be attributed to non‐local wave breaking and dissipation effects: when a mean flow impinges on rough topography and generates lee waves and turbulence, a significant fraction of the generated energy gets advected downstream of the generation site and dissipates remotely. Here, we present a case study for the non‐local lee wave energy dissipation in the South China Sea by using a combination of in situ mooring observations of the bottom flow interacting with two topographic features and corresponding numerical simulations. The results show that most of the near‐inertial and high‐frequency response observed at the mooring site is not locally generated, but rather is produced by the interaction of the subinertial flow with the topographic feature upstream. The wave and turbulent energy detected at the mooring site can be enhanced by an order of magnitude compared to the energy of the locally generated motions. The simulations confirm that up to 70% of the enhanced energy is advected into the region by the subinertial flow, while the rest is radiated into the region as waves. Implication of our results for mixing observations and ocean model parameterizations are discussed.

Numerical investigations of the free surface flow around a surface piercing hydrofoil

Starting with January 2013, naval architects faces new challenges, as all ships greater than 400 tons must comply with energy efficiency index (MPEC 62, 2011). From ship hydrodynamics point of view one handy solution is using Energy Saving Devices (ESD), with the main purpose to improve the flow parameters entering the propeller. For ballast loading condition the ESD may intersect the free surface disturbing and complicating the flow due to free surface /boundary layer interaction, turbulence and breaking wave effects that coexist and which are not completely clarified so far. Therefore, a free surface flow around a NACA 0012 surface piercing hydrofoil is numerically investigated and the results are compared to experimental results obtained in the Towing Tank of the Naval Architecture Faculty, “Dunarea de Jos” University of Galati. The comparison includes drag and free surface elevation on hydrofoil surface together with numerical uncertainty.

Modeling and simulation of large-amplitude ion-acoustic shocklets in degenerate quantized plasmas

Nonlinear propagation and formation of the large-amplitude ion-acoustic (IA) shocklets are studied in a magnetized dense plasma by taking into account the degenerate quantized electrons and classical ions. The ion-fluid equations are nonlinearly coupled and solved together along with a charge-neurality condition to account for the Landau quantization, normalized electron temperature and ion-thermal corrections. Relying on the diagonalization matrix technique, a set of modified characteristic wave equations is derived to support the IA waves both analytically and numerically in a dense quantized plasma. The solitary pulses are found as localized and symmetric at time t=0. However, non-stationary solutions introduce bipolar (asymmetrical) structures in the form of shocklets, that are characterized by the self-steepening and wave breaking effects as long as the time progresses. The excitations of these solitary waves and shocklets become significantly modified in the presence of quantizing magnetic fields, trapped/untrapped electrons and ion-thermal corrections. The present findings are helpful to understand the large-amplitude shock excitations in degenerate dense plasmas, where strong magnetic fields quantize the motion of inertialess electrons.

Investigation of Hirota equation: Modified double Laplace decomposition method

In this article, the non-linear coupled Hirota equations are considered attributed to localized excitations. By employing a modified double Laplace transform decomposition method, we derived the general approximate solutions for the coupled Hirota and coupled Hirota Satsuma equations. It is observed that the proposed method is a systematic and powerful scheme for solving such nonlinear systems. The main advantage of the method is to calculate solutions in a series form without any linearization, discretization, or perturbation. Using convergence analysis, we observed that the proposed method is converging to the exact solution of the system. Numerical analysis for these solutions shows the confine carrier wave and ensures localized wave packets. A degree enhancement reduction in the dispersion nonlinearly coefficients alters both the spatial width and amplitude of the waves. At vanishingly small dispersion, internal oscillations in the pulse-shaped solitary waves reduced the wave breaking effect. We have noticed that the numerical solutions converge to the exact solutions, confirming the importance of the proposed technique.