scholarly journals RESONANT INTERACTIONS FOR WAVES BREAKING.ON A BEACH

1976 ◽  
Vol 1 (15) ◽  
pp. 31 ◽  
Author(s):  
Robert T. Guza ◽  
Anthony J. Bowen
Keyword(s):  
Incident Wave ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Wave ◽  
Edge Waves ◽  
Viscous Effects ◽  
Resonant Interactions ◽  
Maximum Value ◽  
Run Up ◽  
Subharmonic Resonances

A laboratory and theoretical study of the transition from strongly reflected surging to dissipative plunging breakers on a relatively steep plane beach (1:8) has revealed the following: (1) The run-up and offshore variation of sea surface elevation of surging waves are well predicted by linear theory. (2) The fluctuating part of the run-up (related to the amplitude of the reflected incident wave) reaches a maximum value; a further increase in incident progressive wave energy results in increased dissipation. (3) Subharmonic edge waves (the growing instabilities of surging waves) are driven primarily by the swash motion, which does not increase with increasing incident breaking wave height. However, the turbulence accompanying incident wave breaking, and the effective eddy viscosity, rapidly increases with increasing breaker height. As a result, subharmonic resonances do not occur with spilling or steep plunging waves; very strong viscous effects suppress the nonlinear instabilities. (4) edge waves generated by a surging incident wave can be suppressed by superimposing an additional breaking wave of different frequency on the incident wave field. Thus, any excited edge waves are likely to have length scales at least the order of a surf zone width.

scholarly journals Assessment of Numerical Methods for Plunging Breaking Wave Predictions

2021 ◽  
Vol 9 (3) ◽  
pp. 264
Author(s):  
Shanti Bhushan ◽  
Oumnia El Fajri ◽  
Graham Hubbard ◽  
Bradley Chambers ◽  
Christopher Kees
Keyword(s):  
Solitary Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Wave Crest ◽  
Breaking Wave ◽  
Rans Turbulence Models ◽  
Run Up ◽  
Better Than

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

scholarly journals Non-breaking and breaking solitary wave run-up

2002 ◽  
Vol 456 ◽  
pp. 295-318 ◽  
Author(s):  
YING LI ◽  
FREDRIC RAICHLEN
Keyword(s):  
Numerical Model ◽  
Solitary Wave ◽  
Wave Breaking ◽  
Ad Hoc ◽  
Mapping Technique ◽  
Breaking Wave ◽  
Good Prediction ◽  
Computational Domain ◽  
Domain Mapping ◽  
Run Up

The run-up of non-breaking and breaking solitary waves on a uniform plane beach connected to a constant-depth wave tank was investigated experimentally and numerically. If only the general characteristics of the run-up process and the maximum run-up are of interest, for the case of a breaking wave the post-breaking condition can be simplified and represented as a propagating bore. A numerical model using this bore structure to treat the process of wave breaking and subsequent shoreward propagation was developed. The nonlinear shallow water equations (NLSW) were solved using the weighted essentially non-oscillatory (WENO) shock capturing scheme employed in gas dynamics. Wave breaking and post-breaking propagation are handled automatically by this scheme and ad hoc terms are not required. A computational domain mapping technique was used to model the shoreline movement. This numerical scheme was found to provide a relatively simple and reasonably good prediction of various aspects of the run-up process. The energy dissipation associated with wave breaking of solitary wave run-up (excluding the effects of bottom friction) was also estimated using the results from the numerical model.

Research and Analysis on the Wave Transformation and Irregular Wave Breaking Criterion on the Shore

2016 ◽  
Vol 858 ◽  
pp. 354-358
Author(s):  
Tao You ◽  
Li Ping Zhao ◽  
Zheng Xiao ◽  
Lun Chao Huang ◽  
Xiao Rui Han
Keyword(s):  
Theoretical Model ◽  
Wave Height ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Waves ◽  
Wave Transformation ◽  
Breaking Wave ◽  
Height Distribution ◽  
Flume Experiments ◽  
Irregular Wave

Within the surf zone which is the region extending from the seaward boundary of wave breaking to the limit of wave uprush, breaking waves are the dominant hydrodynamics acting as the key role for sediment transport and beach profile change. Breaking waves exhibit various patterns, principally depending on the incident wave steepness and the beach slope. Based on the equations of conservation of mass, momentum and energy, a theoretical model for wave transformation in and outside the surf zone was obtained, which is used to calculate the wave shoaling, wave set-up and set down and wave height distributions in and outside the surf zone. The analysis and comparison were made about the breaking point location and the wave height variation caused by the wave breaking and the bottom friction, and about the wave breaking criterion under regular and irregular breaking waves. Flume experiments relating to the regular and irregular breaking wave height distribution across the surf zone were conducted to verify the theoretical model. The agreement is good between the theoretical and experimental results.

SPH MODELING OF VORTICITY GENERATION BY SHORT-CRESTED WAVE BREAKING

2017 ◽  
pp. 1 ◽  
Author(s):  
Zhangping Wei ◽  
Robert A Dalrymple
Keyword(s):  
Incident Wave ◽  
Wave Breaking ◽  
Circulation Pattern ◽  
Breaking Wave ◽  
Mesh Free ◽  
Wave Basin ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Vorticity Generation ◽  
Incident Waves

This study investigates vorticity generation by short-crested wave breaking by using the mesh-free Smoothed Particle Hydrodynamics model, GPUSPH. The short-crested waves are created by generating intersecting wave trains in a numerical wave basin with a beach. The capability of GPUSPH to simulate short-crested waves is first validated by laboratory measurements. Then we examine short-crested wave breaking with two incident wave heights H = 0.2 m and 0.3 m. The larger incident wave breaks at the toe of the planar beach, while the smaller incident wave breaks above the planar beach. The breaking wave profile, current field, nearshore circulation pattern, and vertical vorticity field due to short-crested wave breaking are carefully compared between two incident waves.

scholarly journals VALIDATION OF A BUOYANCY-MODIFIED TURBULENCE MODEL BY NUMERICAL SIMULATIONS OF BREAKING WAVES OVER A FIXED BAR

2018 ◽  
pp. 71
Author(s):  
Brecht Devolder ◽  
Peter Troch ◽  
Pieter Rauwoens
Keyword(s):  
Numerical Simulations ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Two Phase ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Nearshore Sediment Transport ◽  
Run Up

The surf zone dynamics are governed by important processes such as turbulence generation , nearshore sediment transport , wave run-up and wave overtopping at a coastal structure. During field observations , it is very challenging to measure and quantify wave breaking turbulence . Complementary to experimental laboratory studies in a more controlled environment , numerical simulations are highly suitable to understand and quantify surf zone processes more accurately. In this study, wave propagation and wave breaking over a fixed barred beach profile is investigated using a two­ phase Navier-Stokes flow solver. We show that accurate predictions of the turbulent two-phase flow field require special attention regarding turbulence modelling. The numerical wave flume is implemented in the open­ source OpenFOAM library. The computed results (surface elevations , velocity profiles and turbulence levels) are compared against experimental measurements in a wave flume (van der A et al., 2017) .

Regularly-spaced grooves on shore platforms in north Northumberland, UK

2020 ◽  
Vol 63 (2) ◽  
pp. 124-134
Author(s):  
Alison M. Tymon ◽  
Barry G. Tymon
Keyword(s):  
Incident Wave ◽  
Wave Energy ◽  
Surf Zone ◽  
High Water ◽  
Edge Waves ◽  
Shore Platform ◽  
Bedding Planes ◽  
High Water Mark ◽  
Incident Wave Energy ◽  
Shore Platforms

Unusual regularly-spaced grooves are found between low water mark (LWM) and high water mark (HWM) on several shore platforms in north Northumberland. References in the literature are sparse, so data were collected to establish the nature of the grooves and to elucidate the processes that might have formed them. Groove formation is confined to strata with widely spaced bedding planes on shore platforms dipping at no more than 5° towards the sea. The grooves are symmetrical, bifurcation is common and grooves on sandstones are deeper and more sinuous than those on limestones. Grooves at mid-tide levels are wider than grooves near LWM and HWM and the trend of the grooves is not related to joint trends. The process that has formed the characteristically smooth surfaces of the grooves is considered to be abrasion by sand and pebbles carried by waves in the surf zone of the shore platform. The width of the grooves is remarkably regular, and it is suggested that this may be due to the effects of the increase in incident wave energy given by edge waves.

scholarly journals SURF ZONE WAVE HEATING BY ENERGY DISSIPATION OF BREAKING WAVES

2018 ◽  
pp. 2 ◽  
Author(s):  
Zhangping Wei ◽  
Robert A. Dalrymple
Keyword(s):  
Internal Energy ◽  
Wave Energy ◽  
Water Waves ◽  
Wave Breaking ◽  
Surf Zone ◽  
Current System ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Conservation Of Energy ◽  
Wave Heating

This study investigates surf zone wave heating due to the dissipation of breaking wave energy by using the Smoothed Particle Hydrodynamics method. We evaluate the surf zone wave heating by examining the increase of internal energy of the system, which is computed based on the conservation of energy. The equivalent temperature profile is calculated based on a simple conversion relationship between energy and temperature. We first examine the surf zone wave heating based on long-crested wave breaking over a planar beach, and we consider spilling breaker and weakly plunging breaker. Numerical results show that breaking of water waves in the surf zone increases the internal energy of water body. Furthermore, the dissipation of incident wave energy is fully converted into the internal energy in a thermally isolated system, confirming the energy conservation of the present numerical approach. It is further found that the long-crested wave breaking generates undertow, which transports the generated wave heating from the surf zone to deep waters. We further carry out numerical experiments to examine surf zone wave heating due to short-crested wave breaking over a beach. The internal energy generation mainly follows the isolated wave breakers, and there is a 3D pattern of wave heating due to the complicated wave breaking process and current system. In general, the magnitude of the generated internal energy or temperature by dissipation of breaking wave energy in the surf zone is relatively small. The present study shows that the generated water temperature is in the order of 10^-3 Kelvin for wave breaking over a typical coastal beach.

scholarly journals COMPUTATIONS OF LONGSHORE CURRENTS

1964 ◽  
Vol 1 (9) ◽  
pp. 12
Author(s):  
Tsao-Yi Chiu ◽  
Per Bruun
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Surf Zone ◽  
Wave Spectrum ◽  
Wave Theory ◽  
Breaking Wave ◽  
Height Distribution ◽  
Longshore Current ◽  
Longshore Currents ◽  
Actual Height

This article introduces the longshore current computations based on theories published under the title "Longshore Currents and Longshore Troughs" (Bruun, 1963). Two approaches are used to formulate the longshore current velocities for a beach profile with one bar under the following assumptions: (1) that longshore current is evenly distributed (or a mean can be taken) along the depthj (2) that the solitary wave theory is applicable for waves in the surf zone; (3) that the statistical wave-height distribution for a deep water wave spectrum with a single narrow band of frequencies can be used near the shore, and (4) that the depth over the bar crest, Dcr, equal 0.8Hv/i /o\. Breaking wave height H^Q/^X is designated to be the actual height equal to Hw-j (significant wave height). Diagrams have been constructed for both approaches for beach profiles with one bar, from which longshore current velocities caused by various wave-breaking conditions can be read directly. As for longshore currents along the beach with a multibar system, fifteen diagrams covering a great variety of wave-breaking conditions are provided for obtaining longshore current velocities in different troughs.

scholarly journals The Effect of Wave Breaking on Surf-Zone Turbulence and Alongshore Currents: A Modeling Study*

2005 ◽  
Vol 35 (11) ◽  
pp. 2187-2203 ◽  
Author(s):  
Falk Feddersen ◽  
J. H. Trowbridge
Keyword(s):  
Drag Coefficient ◽  
Water Depth ◽  
Wave Breaking ◽  
Surf Zone ◽  
Model Parameters ◽  
Breaking Wave ◽  
Bottom Stress ◽  
The Mean ◽  
Alongshore Current ◽  
Bed Roughness

Abstract The effect of breaking-wave-generated turbulence on the mean circulation, turbulence, and bottom stress in the surf zone is poorly understood. A one-dimensional vertical coupled turbulence (k–ɛ) and mean-flow model is developed that incorporates the effect of wave breaking with a time-dependent surface turbulence flux and uses existing (published) model closures. No model parameters are tuned to optimize model–data agreement. The model qualitatively reproduces the mean dissipation and production during the most energetic breaking-wave conditions in 4.5-m water depth off of a sandy beach and slightly underpredicts the mean alongshore current. By modeling a cross-shore transect case example from the Duck94 field experiment, the observed surf-zone dissipation depth scaling and the observed mean alongshore current (although slightly underpredicted) are generally reproduced. Wave breaking significantly reduces the modeled vertical shear, suggesting that surf-zone bottom stress cannot be estimated by fitting a logarithmic current profile to alongshore current observations. Model-inferred drag coefficients follow parameterizations (Manning–Strickler) that depend on the bed roughness and inversely on the water depth, although the inverse depth dependence is likely a proxy for some other effect such as wave breaking. Variations in the bed roughness and the percentage of breaking-wave energy entering the water column have a comparable effect on the mean alongshore current and drag coefficient. However, covarying the wave height, forcing, and dissipation and bed roughness separately results in an alongshore current (drag coefficient) only weakly (strongly) dependent on the bed roughness because of the competing effects of increased turbulence, wave forcing, and orbital wave velocities.

scholarly journals WAVE SPECTRUM OF BREAKING WAVE

1976 ◽  
Vol 1 (15) ◽  
pp. 32 ◽  
Author(s):  
Toru Sawaragi ◽  
Koichiro Iwata
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Power Law ◽  
Wave Breaking ◽  
Surf Zone ◽  
Wave Spectrum ◽  
Breaking Wave ◽  
Harmonic Frequency ◽  
Dimensional Consideration

By wave breaking, an incident monocromatic wave is transformed to a wave composed of its harmonic frequency waves inside a surf zone. Based on a dimensional consideration, the "-1 power law ", the "-2 power law ", the "-2/3 power law " and the "-1/2 power law " on the wave height spectrum ,H(f), are derived as sorts of equilibrium spectra. These spectra except"-l/2 power law" are shown to agree with experimental data.

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