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Showing papers on "Breaking wave published in 2020"


Journal ArticleDOI
TL;DR: In this paper, a numerical investigation of the solitary wave breaking over a slope by using a finite particle method (FPM), which is an enhanced smoothed particle hydrodynamics (SPH), is presented.

63 citations


Journal ArticleDOI
TL;DR: In this article, a strong mountain wave is simulated in 2D under two fixed background wind conditions representing opposite tidal phases, and the authors investigate the breaking of the mountain wave and subsequent generation of nonprimary waves in the upper atmosphere.
Abstract: A strong mountain wave, observed over Central Europe on 12 January 2016, is simulated in 2D under two fixed background wind conditions representing opposite tidal phases. The aim of the simulation is to investigate the breaking of the mountain wave and subsequent generation of nonprimary waves in the upper atmosphere. The model results show that the mountain wave first breaks as it approaches a mesospheric critical level creating turbulence on horizontal scales of 8–30 km. These turbulence scales couple directly to horizontal secondary waves scales, but those scales are prevented from reaching the hermosphere by the tidal winds, which act like a filter. Initial secondary waves that can reach the thermosphere range from 60 to 120 km in horizontal scale and are influenced by the scales of the horizontal and vertical forcing associated with wave breaking at mountain wave zonal phase width, and horizontal wavelength scales. Large-scale nonprimary waves dominate over the whole duration of the simulation with horizontal scales of 107–300 km and periods of 11–22 minutes. The thermosphere winds heavily influence the time-averaged spatial distribution of wave forcing in the thermosphere, which peaks at 150 km altitude and occurs both westward and eastward of the source in the 2 UT background simulation and primarily eastward of the source in the 7 UT background simulation. The forcing amplitude is ∼2× that of the primary mountain wave breaking and dissipation. This suggests that nonprimary waves play a significant role in gravity waves dynamics and improved understanding of the thermospheric winds is crucial to understanding their forcing distribution.

61 citations


Journal ArticleDOI
TL;DR: In this paper, the authors consider a range of stellar evolutionary models and incorporate the frequency-dependent effective viscosity acting on equilibrium tides based on the latest simulations, and compare the tidal flow and dissipation obtained with the conventional equilibrium tide, which is strictly invalid in convection zones, finding that the latter typically overpredicts the dissipation by a factor of 2-3.
Abstract: We study tidal dissipation in stars with masses in the range 0.1–1.6 M⊙ throughout their evolution, including turbulent effective viscosity acting on equilibrium tides and inertial waves (IWs) in convection zones, and internal gravity waves in radiation zones. We consider a range of stellar evolutionary models and incorporate the frequency-dependent effective viscosity acting on equilibrium tides based on the latest simulations. We compare the tidal flow and dissipation obtained with the conventional equilibrium tide, which is strictly invalid in convection zones, finding that the latter typically overpredicts the dissipation by a factor of 2–3. Dissipation of IWs is computed using a frequency-averaged formalism accounting for realistic stellar structure for the first time, and is the dominant mechanism for binary circularization and synchronization on the main sequence. Dissipation of gravity waves in the radiation zone assumes these waves to be fully damped (e.g. by wave breaking), and is the dominant mechanism for planetary orbital decay. We calculate the critical planetary mass required for wave breaking as a function of stellar mass and age, and show that this mechanism predicts destruction of many hot Jupiters but probably not Earth-mass planets on the main sequence. We apply our results to compute tidal quality factors following stellar evolution, and tidal evolutionary time-scales, for the orbital decay of hot Jupiters, and the spin synchronization and circularization of binary stars. We also provide predictions for shifts in transit arrival times due to tidally driven orbital decay of hot Jupiters that may be detected with NGTS, TESS, or PLATO.

58 citations



Journal ArticleDOI
TL;DR: In this paper, the authors present direct numerical simulations of breaking solitary waves in shallow water to quantify the energy dissipation during the active breaking time, and they find that this dissipation can be predicted by an inertial model based on Taylor's hypothesis as a function of the local wave height, depth and the beach slope.
Abstract: We present direct numerical simulations of breaking solitary waves in shallow water to quantify the energy dissipation during the active breaking time. We find that this dissipation can be predicted by an inertial model based on Taylor’s hypothesis as a function of the local wave height, depth and the beach slope. We obtain a relationship that gives the dissipation rate of a breaking wave on a shallow slope as a function of local breaking parameters. Next, we use empirical relations to relate the local wave parameters to the offshore conditions. This enables the energy dissipation to be predicted in terms of the initial conditions. We obtain good collapse of the numerical data with respect to the theoretical scaling.

37 citations


Journal ArticleDOI
TL;DR: In this article, a coupled fluid-solid simulation was developed on the basis of a coupled SPH-DEM algorithm, enabling the simulation of the whole process of disaster chains covering failure → motion → wave induction → wave propagation→ wave-dam interaction.
Abstract: Landslide-induced waves are a complex fluid–solid coupling phenomenon. A code for coupled fluid–solid simulation was developed on the basis of a coupled SPH-DEM algorithm, enabling the simulation of the whole process of disaster chains covering “Failure → Motion → Wave induction → Wave propagation→Wave-dam interaction” of landslides. The process of wave disasters induced by the landslides down the reservoir near a dam was studied using this method. The fine 3D model depicting the geological structure of landslides as well as their instability mode was built from field survey. Parameters on the contact mechanical characteristics of DEM particles composing landslides were inverted from experiments. Characteristics on the formation and propagation of landslide-induced waves were derived from numerical simulation based on the SPH-DEM coupling method. These characteristics, such as the height of the waves, their impact force on dams, overtopping flow and velocity, and other quantitative information, provide references to reasonably evaluate their disastrous effect. When landslide materials enter the water and generate waves, the surface water stream moves a certain distance and a strong circular current is formed underwater near the entry point. As the stream propagates, its energy declines. On meeting a barrier, it runs up under inertia and becomes breaking waves, thereby generating a huge impact force. The dynamic force of the waves on the dam is the highest when the first wave arrives. In addition, the dynamic force of the waves mainly acts on the upper parts of the dam.

35 citations


Journal ArticleDOI
TL;DR: In this paper, an overview of breaking waves and liquid sloshing impact acting on rigid walls and in liquid containers is presented, together with the dimensionless parameters governing the design of small-scale models.
Abstract: This article presents an overview of breaking waves and liquid sloshing impact acting on rigid walls and in liquid containers. The physics of breaking waves against rigid walls can be understood through the Bagnold/Mitsuyasu piston theory. The flip-through is a major feature associated with the occurrence of violent waves without any actual impact on the wall. The physics of the phase transition during liquid impacts involves two- and multi-phase flows due to the entrapped gas pockets is addressed. The liquid sloshing assessment of liquefied natural gas tanks together with the dimensionless parameters governing the design of small-scale models is discussed. The nonlinear liquid sloshing dynamics under sway and rotational excitations is described for different container geometries. This article will discuss recent developments of numerical algorithms and computer codes capable to describe breaking waves and extreme sloshing impacts. Moreover, recent advances in breaking Faraday waves are also addressed together with an assessment of breaking interfacial gravity waves, in which a multilayer or stratified medium is a stack of different thin layers.

30 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the validity and robustness of the Barthelemy et al. (2018) breaking wave onset prediction framework for surface gravity water waves in arbitrary water depth, including shallow water breaking over varying bathymetry.
Abstract: We investigate the validity and robustness of the Barthelemy et al. (2018) breaking wave onset prediction framework for surface gravity water waves in arbitrary water depth, including shallow water breaking over varying bathymetry. We show that the Barthelemy et al. (2018) breaking onset criterion, which they validated for deep and intermediate water depths, also segregates breaking crests from non-breaking crests in shallow water, with subsequent breaking always following the exceedance of their proposed generic breaking threshold. We consider a number of representative wave types, including regular, irregular, solitary, and focused waves, shoaling over idealized bed topographies including an idealized bar geometry and a mildly- to steeply-sloping planar beach. Our results show that the new breaking onset criterion is capable of detecting single and multiple breaking events in time and space in arbitrary water depth. Further, we show that the new generic criterion provides improved skill for signaling imminent breaking onset, relative to the available kinematic or geometric breaking onset criteria in the literature. In particular, the new criterion is suitable for use in wave-resolving models that cannot intrinsically detect the onset of wave breaking.

29 citations


Journal ArticleDOI
TL;DR: In this article, the authors present an analytical toolkit for population balance analysis in two-phase flows, including the expected -10/3 power-law exponent for the super-Hinze-scale size distribution, which suggests the emergence of different physical mechanisms during different phases of the breaking wave evolution.
Abstract: Breaking waves generate a distribution of bubble sizes that evolves over time. Knowledge of how this distribution evolves is of practical importance for maritime and climate studies. The analytical framework developed in Part 1 examined how this evolution is governed by the bubble-mass flux from large to small bubble sizes, which depends on the rate of break-up events and the distribution of child bubble sizes. These statistics are measured in Part 2 as ensemble-averaged functions of time by simulating ensembles of breaking waves, and identifying and tracking individual bubbles and their break-up events. The break-up dynamics are seen to be statistically unsteady, and two intervals with distinct characteristics were identified. In the first interval, the dissipation rate and bubble-mass flux are quasi-steady, and the theoretical analysis of Part 1 is supported by all observed statistics, including the expected -10/3 power-law exponent for the super-Hinze-scale size distribution. Strong locality is observed in the corresponding bubble-mass flux, supporting the presence of a super-Hinze-scale break-up cascade. In the second interval, the dissipation rate decays, and the bubble-mass flux increases as small- and intermediate-sized bubbles become more populous. This flux remains strongly local with cascade-like behaviour, but the dominant power-law exponent for the size distribution increases to -8/3 as small bubbles are also depleted more quickly. This suggests the emergence of different physical mechanisms during different phases of the breaking-wave evolution, although size-local break-up remains a dominant theme. Parts 1 and 2 present an analytical toolkit for population balance analysis in two-phase flows.

29 citations


Journal ArticleDOI
02 Apr 2020-Water
TL;DR: In this paper, the effects of breakwaters on sediment transport and marsh evolution under different wave regimes using Delft3D-SWAN, a dynamic geomorphodynamic numerical model.
Abstract: Human encroachment and development on coastlines have led to greater amounts of armoring of shorelines. Breakwaters are a common feature along coastlines, which are used to dampen wave energy and protect shorelines from flash floods or overwash events. Although common, their effects on sediment transport and marsh geomorphology are poorly understood. To address this gap, our study quantifies the effects of breakwaters on sediment transport and marsh evolution under different wave regimes using Delft3D-SWAN, a dynamic geomorphodynamic numerical model. Model configurations used the same numerical domain, but scenarios had different sediments, waves, tides, basin slopes and breakwater distances from the shoreline to explore how waves and tidal currents shape coastal margins. Model results suggested breakwaters were responsible for an average wave damping between 10–50%, proportional to the significant wave height across all modeled scenarios. Shear stress at the beginning of the marsh and the volume of sediment deposited at the end of the simulation (into the marsh behind the breakwater) increased on average between 20–40%, proportional to the slope and distance of the breakwater from the shoreline. Sediment trapping, defined as the ratio between the volume of sediment housed into the salt marsh behind and away from the breakwater, was found to be less than 1 from most model runs. Study results indicated that breakwaters are advantageous for wave breaking to protect shorelines from the wave’s energy, however, they might also be an obstacle for sediment transport, negatively affecting nourishment processes, and, consequently, impeded long-term salt marsh survival. Identifying a balance between waves dampening and shoreline nourishment should be considered in the design and implementation of these structures.

27 citations


Journal ArticleDOI
TL;DR: In this article, a numerical study of current effects on waves (CEW) at sub-mesoscales (100's of m-10's of km) with a realistic model configuration in Southern California is presented.

Posted Content
TL;DR: In this article, the authors proved wave breaking for the Burgers-Hilbert equation, the fractional Korteweg-de Vries equation, and the classical Whitham equation.
Abstract: We prove wave breaking (shock formation) for some Whitham-type equations which include the Burgers-Hilbert equation, the fractional Korteweg-de Vries equation, and the classical Whitham equation. The result seems to be new for the Burgers-Hilbert equation. In the other cases we provide simpler proofs than the known ones.

Journal ArticleDOI
TL;DR: In this article, a two-phase flow Computational Fluid Dynamics (CFD) model is employed for both spilling and plunging breaking wave simulations, and a numerical wave tank is built to evaluate the performance of two different free surface modelling approaches (i.e., continuous free surface conditions and free surface jump conditions) and three k − ω SST turbulence models (a newly proposed model)).

Journal ArticleDOI
TL;DR: In this paper, the authors review the derivation of many of the most important models that appear in the literature (mainly in coastal oceanography) for the description of waves in shallow water, and show that these models can be obtained using various asymptotic expansions of the turbulent and non-hydrostatic terms that appeared in the equations that result from the vertical integration of the free surface Euler equations.
Abstract: We review here the derivation of many of the most important models that appear in the literature (mainly in coastal oceanography) for the description of waves in shallow water. We show that these models can be obtained using various asymptotic expansions of the "turbulent" and non-hydrostatic terms that appear in the equations that result from the vertical integration of the free surface Euler equations. Among these models are the well-known nonlinear shallow water (NSW), Boussinesq and Serre-Green-Naghdi (SGN) equations for which we review several pending open problems. More recent models such as the multi-layer NSW or SGN systems, as well as the Isobe-Kakinuma equations are also reviewed under a unified formalism that should simplify comparisons. We also comment on the scalar versions of the various shallow water systems which can be used to describe unidirectional waves in horizontal dimension $d=1$; among them are the KdV, BBM, Camassa-Holm and Whitham equations. Finally, we show how to take vorticity effects into account in shallow water modeling, with specific focus on the behavior of the turbulent terms. As examples of challenges that go beyond the present scope of mathematical justification, we review recent works using shallow water models with vorticity to describe wave breaking, and also derive models for the propagation of shallow water waves over strong currents.

Journal ArticleDOI
TL;DR: A theoretical model supported by three-dimensional numerical simulations is developed to explain the transverse instability growth from noise to wave breaking and its crucial effect on stopping the acceleration of ultrathin foils.
Abstract: Acceleration of ultrathin foils by the laser radiation pressure promises a compact alternative to the conventional ion sources. Among the challenges on the way to practical realization, one fundamental is a strong transverse plasma instability, which develops density perturbations and breaks the acceleration. In this Letter, we develop a theoretical model supported by three-dimensional numerical simulations to explain the transverse instability growth from noise to wave breaking and its crucial effect on stopping the acceleration. The wave-broken nonlinear mode triggers rapid stochastic heating that finally explodes the target. Possible paths to mitigate this problem for getting efficient ion acceleration are discussed.

Journal ArticleDOI
TL;DR: In this article, an Incompressible Smoothed Particle Hydrodynamics (ISPH) method with the k-e turbulence closure is presented, which can be applied to transient free surface wave problems.

Journal ArticleDOI
TL;DR: In this article, the authors characterize and quantify the prevalent physical processes in the energy transformation of a regular wave train when it interacts with permeable and impermeable breakwaters, and show that the Iribarren number is not a sufficient similarity parameter for the analysis of wave breaking and related flow characteristics on slopes.

Journal ArticleDOI
TL;DR: In this paper, a weakly compressible smoothed particle (WCSPH) model, coupled with a two-equation model for turbulent stresses, has been employed for this scope.
Abstract: The present paper, places emphasis on the vorticity induced by wave breaking, which greatly contributes to sediments pick up and suspension as well as to air–water exchange at the wave interface, thus deserving a thorough study. A weakly-compressible smoothed particle (WCSPH) model, coupled with a two-equation model for turbulent stresses, has been employed for this scope. A careful calibration of the SPH’s numerical parameters has been first performed, based on experiments carried out in a sloped wave channel, specifically using wave elevation and velocity data. Once proved the reliable performance of the model, the characteristics of vorticity induced just prior and post breaking for both the cases of a spilling and a plunging wave have been numerically studied. The main and detailed results indicate that for both the types of breakers there is a cause-effect relation observed between the stream wise flow deceleration and the vorticity generation.

Journal ArticleDOI
TL;DR: The authors analytically quantify locality by extending the population balance equation in conservative form to derive the bubble-mass transfer rate from large to small sizes, and show that scalings relevant to turbulent bubbly flows, including those postulated by Garrett et al. (2000) and observed in breaking-wave experiments and simulations, are consistent with a strongly local transfer rate.
Abstract: Breaking waves entrain gas beneath the surface. The wave-breaking process energizes turbulent fluctuations that break bubbles in quick succession to generate a wide range of bubble sizes. Understanding this generation mechanism paves the way towards the development of predictive models for large-scale maritime and climate simulations. Garrett et al. (2000) suggested that super-Hinze-scale turbulent breakup transfers entrained gas from large to small bubble sizes in the manner of a cascade. We provide a theoretical basis for this bubble-mass cascade by appealing to how energy is transferred from large to small scales in the energy cascade central to single-phase turbulence theories. A bubble break-up cascade requires that break-up events predominantly transfer bubble mass from a certain bubble size to a slightly smaller size on average. This property is called locality. In this paper, we analytically quantify locality by extending the population balance equation in conservative form to derive the bubble-mass transfer rate from large to small sizes. Using our proposed measures of locality, we show that scalings relevant to turbulent bubbly flows, including those postulated by Garrett et al. (2000) and observed in breaking-wave experiments and simulations, are consistent with a strongly local transfer rate, where the influence of non-local contributions decays in a power-law fashion. These theoretical predictions are confirmed using numerical simulations in Part 2, revealing key physical aspects of the bubble break-up cascade phenomenology. Locality supports the universality of turbulent small-bubble break-up, which simplifies the development of subgrid-scale models to predict oceanic small-bubble statistics of practical importance.

Journal ArticleDOI
TL;DR: In this paper, the evolution of different wave components as they propagate within a microtidal inlet during a storm occurring from 24-26 January 2014 is analyzed, in order to improve knowledge on how micro-tidal river mouths typical of the Adriatic Sea behave.
Abstract: The evolution of different wave components as they propagate within a microtidal inlet during a storm occurring from 24–26 January 2014 is analysed, in order to improve knowledge on how microtidal river mouths typical of the Adriatic Sea behave. For the first time, the “low-pass filter” mechanism previously ascertained at several macrotidal oceanic inlets around the world has been observed in the field with remarkably specific hydrodynamic conditions, i.e. low tide excursion, permanent connection with the sea and generally milder wave climate than in the ocean. Sea/swell (SS) waves were strongly dissipated before entering the river mouth, through the combined action of wave breaking due to reducing depths and opposing river currents enhanced by rainfall. Infragravity (IG) waves propagated upstream and significant IG wave heights of up to 0.4 m, about 13% of the local water depth, have been observed 400 m upriver (about 10 times the local SS peak wavelength) during storm climax. The IG wave energy here represented over 4% of the maximum offshore storm energy. IG wave components travelled upriver at estimated velocities between 3.6 m/s and 5.5 m/s (comparable with speeds of nonlinear long waves) during intense storm stages up to 600 m into the river channel (about 15 times the local SS peak wavelength), and are enhanced by tide-induced increase in water depths. It is estimated that tide-induced excursion accounted for about 80% of the total mean water elevation at storm peak at about 400 m into the river. Finally, tidal oscillations are detected up to 1.5 km upstream (about 40 times the local SS peak wavelength). This study highlights the dominance of astronomical tide over both wave setup and storm surge in controlling the upriver propagation of IG waves, even in a microtidal environment.

Journal ArticleDOI
TL;DR: This work explored what types of coastal imagery can be best utilized in a 2-dimensional fully convolutional neural network to directly estimate nearshore bathymetry from optical expressions of wave kinematics to provide additional actionable information about the spatial reliability of each bathymetric prediction.
Abstract: Resolving surf-zone bathymetry from high-resolution imagery typically involves measuring wave speeds and performing a physics-based inversion process using linear wave theory, or data assimilation techniques which combine multiple remotely sensed parameters with numerical models. In this work, we explored what types of coastal imagery can be best utilized in a 2-dimensional fully convolutional neural network to directly estimate nearshore bathymetry from optical expressions of wave kinematics. Specifically, we explored utilizing time-averaged images (timex) of the surf-zone, which can be used as a proxy for wave dissipation, as well as including a single-frame image input, which has visible patterns of wave refraction and instantaneous expressions of wave breaking. Our results show both types of imagery can be used to estimate nearshore bathymetry. However, the single-frame imagery provides more complete information across the domain, decreasing the error over the test set by approximately 10% relative to using timex imagery alone. A network incorporating both inputs had the best performance, with an overall root-mean-squared-error of 0.39 m. Activation maps demonstrate the additional information provided by the single-frame imagery in non-breaking wave areas which aid in prediction. Uncertainty in model predictions is explored through three techniques (Monte Carlo (MC) dropout, infer-transformation, and infer-noise) to provide additional actionable information about the spatial reliability of each bathymetric prediction.

Journal ArticleDOI
TL;DR: In this paper, the effects of breaking wave loads on a 10MW large-scale monopile offshore wind turbine under typical sea conditions in the eastern seas of China were investigated based on Fifth-Order Stokes wave theory.
Abstract: In the present paper, the computational fluid dynamics method is used to investigate the effects of breaking wave loads on a 10-MW large-scale monopile offshore wind turbine under typical sea conditions in the eastern seas of China Based on Fifth-Order Stokes wave theory a user-defined function is developed and used for wave numerical modelling, and a numerical wave tank with different bottom slopes is developed Τhe effects of different types of breaking waves, such as spilling and plunging waves, on the wave run-up, pressure distribution and horizontal wave force of a large diameter monopile are investigated Different numerical and analytical methods for calculating the wave breaking loads are used and their results are compared with the relevant results of the developed computational fluid dynamics model and their respective scopes of application are discussed With an increase in wave height, the change in the hydrodynamic performance of breaking waves observed through the transition from plunging to spilling waves is explored The intensity of interactions occurring between the breaking waves and the monopile foundation depends mainly on the form of wave breaking involved and its relationship to wave steepness is weak Analytical methods for calculating the breaking wave loads are preservative especially for plunging breaking wave loads

Journal ArticleDOI
TL;DR: In this article, strong turbulence was encountered by the German High-Altitude Long-Range Research Aircraft (HALO) at flight level 430 (13.8 km) on 13 October 2016 above Iceland.
Abstract: Strong turbulence was encountered by the German High-Altitude Long-Range Research Aircraft (HALO) at flight level 430 (13.8 km) on 13 October 2016 above Iceland. In this event the turbulenc...

Journal ArticleDOI
TL;DR: In this article, a new set of higher-order depth-averaged non-hydrostatic equations is presented, which consist in the SGN equations plus additional higher order contributions originating from the variation with elevation of the velocity profile, modeled here with a Picard iteration of the potential flow equations.
Abstract: The water waves resulting from the collapse of a dam are important unsteady free surface flows in civil and environmental engineering Considering the basic case of ideal dam break waves in a horizontal and rectangular channel the wave patterns observed experimentally depends on the initial depths downstream (hd) and upstream (ho) of the dam For r = hd/ho above the transition domain 04–055, the surge travelling downstream is undular, a feature described by the dispersive Serre–Green–Naghdi (SGN) equations In contrast, for r below this transition domain, the surge is broken and it is well described by the weak solution of the Saint–Venant equations, called Shallow Water Equations (SWE) Hybrid models combining SGN–SWE equations are thus used in practice, typically implementing wave breaking modules resorting to several criteria to define the onset of breaking, frequently involving case-dependent calibration of parameters In this work, a new set of higher-order depth-averaged non-hydrostatic equations is presented The equations consist in the SGN equations plus additional higher-order contributions originating from the variation with elevation of the velocity profile, modeled here with a Picard iteration of the potential flow equations It is demonstrated that the higher-order terms confer wave breaking ability to the model without using any empirical parameter, such while, for r > 04–055, the model results are essentially identical to the SGN equations but, for r < 04–055, wave breaking is automatically accounted for, thereby producing broken waves as part of the solution The transition from undular to broken surges predicted by the high-order equations is gradual and in good agreement with experimental observations Using the solution of the new higher-order equations it was further developed a new wave breaking index based on the acceleration at the free surface to its use in hybrid SGN–SWE models

Journal ArticleDOI
TL;DR: Two new practical methods for estimating the breaking wave height from digital images collected by shore-based video monitoring systems using time-exposure (Timex) images and exploiting the cross-shore length of the typical time-averaged signature of breaking wave foam are presented.
Abstract: The breaking wave height is a crucial parameter for coastal studies but direct measurements constitute a difficult task due to logistical and technical constraints. This paper presents two new practical methods for estimating the breaking wave height from digital images collected by shore-based video monitoring systems. Both methods use time-exposure (Timex) images and exploit the cross-shore length ( L H s ) of the typical time-averaged signature of breaking wave foam. The first method ( H s b , v ) combines L H s and a series of video-derived parameters with the beach profile elevation to obtain the breaking wave height through an empirical formulation. The second method ( H s b , v 24 ) is based on the empirical finding that L H s can be associated with the local water depth at breaking, thus it can be used to estimate the breaking wave height without the requirement of local bathymetry. Both methods were applied and verified against field data collected at the Portuguese Atlantic coast over two days using video acquired by an online-streaming surfcam. Furthermore, H s b , v 24 was applied on coastal images acquired at four additional field sites during distinct hydrodynamic conditions, and the results were compared to a series of different wave sources. Achievements suggest that H s b , v method represents a good alternative to numerical hydrodynamic modeling when local bathymetry is available. In fact, the differences against modeled breaking wave height, ranging from 1 to 3 m at the case study, returned a root-mean-square-error of 0.2 m. The H s b , v 24 method, when applied on video data collected at five sites, assessed a normalized root-mean-square-error of 18% on average, for dataset of about 900 records and breaking wave height ranging between 0.1 and 3.8 m. These differences demonstrate the potential of H s b , v 24 in estimating breaking wave height merely using Timex images, with the main advantage of not requiring the beach profile. Both methods can be easily implemented as cost-effective tools for hydrodynamic applications in the operational coastal video systems worldwide. In addition, the methods have the potential to be coupled to the numerous other Timex applications for morphodynamic studies.

Journal ArticleDOI
TL;DR: In this article, wave-current interactions were investigated in the Alderney Race hydrodynamic by the use of numerical modeling and in-situ measurements, showing that wave enhancement of the bottom friction reduced the tidal current, refraction of waves by the current, generating changes in waves directions, and wave breaking ascribed to tidal currents, increasing the turbulent mixing.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the importance of wave-current interaction in the northern Bay of Bengal (BoB) using a fully coupled three-dimensional Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modelling system.
Abstract: The impact of waves on currents and vice-versa is an integral part of the complex coastal dynamics. The wave-current interaction is prominent in the coastal shelf-slope regions, particularly during the passage of a tropical cyclone. In the present study, we describe the importance of wave-current interaction in the northern Bay of Bengal (BoB) using a fully coupled three-dimensional Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modelling system. The COAWST model is applied to the case of a very severe cyclonic storm Phailin that passed over the BoB basin during 10–15 October 2013. To represent the interaction between waves and currents, we utilized the newly implemented vortex-force method in the coupled model. Numerical experiments with different coupling configuration within the COAWST modelling framework were performed to separately identify the effects of wind, tide, and wave-current interaction process. A comparison of model results with the buoy observations of water elevations, currents, and wave measurements shows a good agreement between model and observed data. Various terms of the momentum balance were calculated from the model simulated and diagnosed parameters. A comparison of the horizontal momentum balance term identifies the wave-breaking induced acceleration as one of the leading terms along the storm affected the east coast of India. Further, an increase in the apparent bed roughness caused by waves found to affect the values and distribution of the bottom shear stress. The pressure gradient term showed significant changes to the pure tidal case. The study highlights that the changes in the momentum balance caused by waves includes contributions from the variations in the water level and currents. The most relevant effect on the coastal hydrodynamics was in the form of a wave-induced setup near the location of landfall of the cyclone.


Journal ArticleDOI
TL;DR: In this paper, the authors used two-way nesting in a numerical model with the finest horizontal spacing of 370 m to investigate possible mechanisms producing turbulence in two distinct regions of the cyclone.
Abstract: A large midlatitude cyclone occurred over the central United States from 0000 to 1800 UTC 30 April 2017. During this period, there were more than 1100 reports of moderate-or-greater turbulence at commercial aviation cruising altitudes east of the Rocky Mountains. Much of this turbulence was located above or, otherwise, outside the synoptic-scale cloud shield of the cyclone, thus complicating its avoidance. In this study we use two-way nesting in a numerical model with finest horizontal spacing of 370 m to investigate possible mechanisms producing turbulence in two distinct regions of the cyclone. In both regions, model-parameterized turbulence kinetic energy compares well to observed turbulence reports. Despite being outside of hazardous large radar reflectivity locations in deep convection, both regions experienced strong modification of the turbulence environment as a result of upper-tropospheric/lower-stratospheric (UTLS) convective outflow. For one region, where turbulence was isolated and short lived, simulations revealed breaking of ~100-km horizontal-wavelength lower-stratospheric gravity waves in the exit region of a UTLS jet streak as the most likely mechanism for the observed turbulence. Although similar waves occurred in a simulation without convection, the altitude at which wave breaking occurred in the control simulation was strongly affected by UTLS outflow from distant deep convection. In the other analyzed region, turbulence was more persistent and widespread. There, overturning waves of much shorter 5–10-km horizontal wavelengths occurred within layers of gradient Richardson number < 0.25, which promoted Kelvin–Helmholtz instability associated with strong vertical shear in different horizontal locations both above and beneath the convectively enhanced UTLS jet.

Journal ArticleDOI
TL;DR: In this paper, an extensive laboratory study of wave-in-deck (wid) loading has been conducted, with the aim being to provide an improved physical understanding of wid loading in a wide range of incident wave conditions.