scholarly journals APPLICATIONS OF A NUMERICAL SHALLOW WATER WAVES MODEL

1982 ◽  
Vol 1 (18) ◽  
pp. 54
Author(s):  
A. Hauguel ◽  
Ph. Pechon
Keyword(s):  
Numerical Model ◽  
Water Waves ◽  
Breaking Waves ◽  
Scale Model ◽  
Dimensional Model ◽  
Longshore Current ◽  
Shallow Water Waves ◽  
Storm Waves ◽  
Mean Sea Surface ◽  
The Mean

This paper relates three applications of a numerical model of storm waves in shallow waters developed in LNH. The equations are recalled at first and then the applications performed are presented. The numerical model has been used in the case of the port of Fecamp, on the English Channel coast, on which the results of a scale model were available. The computed results compare well with the scale model measurements. The second case is the s imulation of a t sumami induced by a submarine landslide which appeared in 1979 near Nice ; the mode 1 has permitted the simulation of the rising of the wave. The last applications consisted in simulating breaking waves by introducing a dispersion term in the equations. This simulation has been tested with a one-dimensional model at first. The results show that the numerical model reproduces the elevation of the mean sea surface due to the loss of energy in breakings. Then the longshore current induced by breaking waves coming obliquely over a rectilinear sloping shore has been reproduced with a two dimensional model. The results show that the model is able to compute with a good accuracy re fraction, diffraction and reflection, and that it appears to be very interesting for longshore currents simulation.

Manoeuvring Study of a Container Ship in Shallow Water Waves

2018 ◽  
Author(s):  
Manases Tello Ruiz ◽  
Marc Mansuy ◽  
Guillaume Delefortrie ◽  
Marc Vantorre
Keyword(s):  
Shallow Water ◽  
Water Waves ◽  
Numerical Study ◽  
Scale Model ◽  
Wave Forces ◽  
Shallow Water Waves ◽  
The North ◽  
Captive Model Tests ◽  
Calm Water ◽  
Large Container

When approaching or leaving a port a ship often needs to perform manoeuvres in the presence of waves. At the same time the water depth is still limited for deep drafted vessels. For manoeuvring simulation purposes this requires a manoeuvring model which includes phenomena such as short crested waves and squat effects. The present paper addresses the manoeuvring problem in shallow water waves numerically and experimentally. The numerical study is conducted by means of potential theory, incorporating first and second order exciting wave forces, and their superposition to the calm water manoeuvring models. The applicability of such an approach is also investigated. The experimental work has been conducted at Flanders Hydraulics Research (in cooperation with Ghent University) with a scale model of an ultra large container vessel. Captive model tests comprise harmonic yaw tests and steady straight line tests with and without waves, at different forward speeds, wave frequencies and amplitudes, in head and following waves. Waves are chosen to represent conditions commonly met by ships in the Belgian coastal zone of the North Sea.

Wave-in-Deck Loads for an Intricate Pile-Supported Pier and Variation With Deck Clearance

2013 ◽  
Author(s):  
Andrew Cornett ◽  
David Anglin ◽  
Trevor Elliott
Keyword(s):  
Water Waves ◽  
Three Dimensional ◽  
Wave Structure ◽  
Physical Modelling ◽  
Interaction Process ◽  
Air Gap ◽  
Scale Model ◽  
Shallow Water Waves ◽  
Structure Interaction ◽  
Wave Structure Interaction

Many deck structures are located at elevations low enough to be impacted by large waves. However, due to the highly complex and impulsive nature of the interactions between wave crests and intricate deck structures, establishing reliable estimates of extreme pressures and forces for use in design remains challenging. In this paper, results from an extensive set of three-dimensional scale model tests conducted to support the design of a large pile-supported pier (or jetty) are presented and discussed. Relationships between maximum wave-in-deck loads and the deck clearance (air gap) are presented and discussed. Results from numerical simulations of the wave-structure interaction process obtained using the three-dimensional CFD software FLOW-3D® are also presented and discussed. Finally, some initial comparisons between the numerical and physical modelling are also included. This paper provides new insights concerning the character and magnitude of the hydrodynamic pressures and loads exerted on intricate pile-supported deck structures due to impact by non-linear shallow-water waves, and the relationships between the hydrodynamic forcing and the deck clearance or air gap.

scholarly journals SOME CHARACTERISTICS OF BREAKING WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 26 ◽  
Author(s):  
Frederic Raichlen ◽  
Panos Papanicolaou
Keyword(s):  
Solitary Waves ◽  
Water Waves ◽  
Breaking Waves ◽  
Extensive Study ◽  
Shallow Water Waves ◽  
Engineering Research ◽  
Before And After ◽  
Particle Velocities ◽  
High Degree ◽  
Oscillatory Waves

In recent years there has been a surge in coastal engineering research devoted to various aspects of breaking waves including their kinematics at and after breaking. For a review of certain aspects of this field the interested reader is referred to Peregrine (1983) and Battjes (1988); in this discussion only certain publications pertinent to this investigation will be mentioned briefly. With the advent of laser-Doppler velocimetry (LDV) a number of investigators have measured the internal velocities of waves both before, at, and after breaking. For example, Nadaoka (1986) measured the velocities in the shoaling region under periodic breaking shallow water waves. This extensive study of the nearshore regions resulted in vector diagrams which described very well several spatial aspects of the flow shoreward of breaking. Skjelbreia (1987) also used LDV techniques to define the kinematic characteristics of breaking solitary waves. Measurements were made of the water particle velocities under spilling and plunging breaking waves both very near breaking and after breaking, close to the water surface and to the bottom. A high degree of reproducibility was possible with the laboratory wave generation system used so experiments were conducted at different locations with essentially the same wave; this will be discussed more fully later. Skjelbreia (1987) also presented vector diagrams of the velocities under plunging and spilling solitary breakers. These measurements when compared to those of Nadoaka (1986) raise several questions regarding similarities and differences between breaking oscillatory waves and waves of translation. In addition to detailed kinematic measurements, a macroscopic view of shoaling solitary waves was also taken by Skjelbreia (1987) yielding results on the variation of the wave height with distance both before and after breaking. Although there has been a considerable amount of work along these lines in the past, observations of the changes in the wave at and after breaking are still quite useful in developing an overall understanding of the breaking process.

Hydraulic control of homogeneous shear flows

2003 ◽  
Vol 475 ◽  
pp. 163-172 ◽  
Author(s):  
CHRIS GARRETT ◽  
FRANK GERDES
Keyword(s):  
Shear Flow ◽  
Velocity Profile ◽  
Water Waves ◽  
Flow Speed ◽  
Hydraulic Control ◽  
Mean Flow ◽  
Shallow Water Waves ◽  
Homogeneous Fluid ◽  
Apparent Paradox ◽  
The Mean

If a shear flow of a homogeneous fluid preserves the shape of its velocity profile, a standard formula for the condition for hydraulic control suggests that this is achieved when the depth-averaged flow speed is less than (gh)1/2. On the other hand, shallow-water waves have a speed relative to the mean flow of more than (gh)1/2, suggesting that information could propagate upstream. This apparent paradox is resolved by showing that the internal stress required to maintain a constant velocity profile depends on flow derivatives along the channel, thus altering the wave speed without introducing damping. By contrast, an inviscid shear flow does not maintain the same profile shape, but it can be shown that long waves are stationary at a position of hydraulic control.

scholarly journals EVOLUTION OF DAMAGED ARMOR LAYER PROFILE

2011 ◽  
Vol 1 (32) ◽  
pp. 40
Author(s):  
Ali Farhadzadeh ◽  
Nobuhisa Kobayashi ◽  
Jeffrey Melby
Keyword(s):  
Water Depth ◽  
Hydrodynamic Model ◽  
Water Waves ◽  
Shallow Water Waves ◽  
Irregular Wave ◽  
Progression Model ◽  
Damage Progression ◽  
Dry Zone ◽  
The Mean ◽  
Exponential Probability

A probabilistic hydrodynamic model for the wet and dry zone on a permeable structure is developed to predict irregular wave action on the structure above the still water level. The model is based on the time-averaged continuity and momentum equations for nonlinear shallow-water waves coupled with the exponential probability distribution of the water depth. The model predicts the cross-shore variations of the mean and standard deviation of the water depth and horizontal velocity. Damage progression of a stone armor layer is predicted by modifying a formula for bed load on beaches with input from the hydrodynamic model. The damage progression model is compared with three tests by Melby and Kobayashi (1998) that lasted up to 28.5 hours. The model predicts the temporal progression of the eroded area quite well. The numerical model is very efficient and suited for a risk-based design of rubble mound structures.

Analysis of Numerical Simulation on Near Surface Beneath Clean and Contaminated Small-Scale Wind-Driven Water Waves

2007 ◽  
Author(s):  
Xiaoxia Hu ◽  
Ali Dolatabadi ◽  
Kamran Siddiqul
Keyword(s):  
Numerical Model ◽  
Water Waves ◽  
Numerical Study ◽  
Surface Region ◽  
Surface Flow ◽  
Small Scale ◽  
Mean Velocity ◽  
Near Surface ◽  
The Mean ◽  
Good Agreement

We report on a numerical study conducted to investigate the near-surface flow beneath clean and contaminated small-scale wind-driven water surfaces. The numerical model is validated in terms of the velocity and surface wave characteristics. A good agreement is observed between the experimental and numerical values. The results from the numerical model show that the mean velocity in the near-surface region is 25–50% higher beneath the contaminated surface as compared to the clear surface. The present trend is also in agreement with the previous experimental observations.

The mean forces exerted by waves on floating or submerged bodies with applications to sand bars and wave power machines

1977 ◽  
Vol 352 (1671) ◽  
pp. 463-480 ◽  
Keyword(s):  
Water Waves ◽  
Second Harmonic ◽  
Breaking Waves ◽  
The Body ◽  
Wave Power ◽  
Sand Bars ◽  
The Mean ◽  
Horizontal Momentum ◽  
Set Up ◽  
Energy And Momentum

Water waves transport both energy and momentum, and any solid body which absorbs or reflects wave energy must absorb or reflect horizontal momentum also. Hence the body is subject to a mean horizontal force. In low waves, the force may be calculated immediately when the incident, reflected and transmitted wave amplitudes are known. For wave power devices the mean force can be large, so that anchoring presents practical problems. Experiments with models of the Cockerell wave-raft and the Salter ‘duck’ accurately confirm the predicted magnitude of the force at low wave amplitudes. For steeper waves, however, the magnitude of the force can be less than that given by linear theory. By experiments with submerged cylinders, it is shown that this is due partly to the presence of a free second harmonic on the down-wave side. In breaking waves, it is confirmed that the mean force on submerged bodies is sometimes reduced, and even reversed. An explanation is suggested in terms of the ‘wave set-up’ produced by breaking waves. Submerged cylinders act as a kind of double beach. A negative mean force arises from an asymmetry in the breaking waves, associated with a time-delay in the response to the change in depth. Similar arguments apply to submerged reefs and sand bars. Experiments with a model bar show that long low waves propel the bar towards the shore, whereas steep, breaking waves propel it seawards. This is similar to the observed behaviour of off-shore sand bars. The existence of a horizontal momentum flux (or radiation stress) in water waves is demonstrated by using it to propel a small craft.

scholarly journals Turbulence structure and interaction with steep breaking waves

2011 ◽  
Vol 674 ◽  
pp. 522-577 ◽  
Author(s):  
DJAMEL LAKEHAL ◽  
PETAR LIOVIC
Keyword(s):  
Fluid Flow ◽  
Water Waves ◽  
Three Dimensional ◽  
Breaking Waves ◽  
Small Scale ◽  
Breaking Wave ◽  
Turbulence Structure ◽  
Mean Flow ◽  
Scale Breaking ◽  
The Mean

Large-eddy and interface simulation using an interface tracking-based multi-fluid flow solver is conducted to investigate the breaking of steep water waves on a beach of constant bed slope. The present investigation focuses mainly on the ‘weak plunger’ breaking wave type and provides a detailed analysis of the two-way interaction between the mean fluid flow and the sub-modal motions, encompassing wave dynamics and turbulence. The flow is analysed from two points of views: mean to sub-modal exchange, and wave to turbulence interaction within the sub-modal range. Wave growth and propagation are due to energy transfer from the mean flow to the waves, and transport of mean momentum by these waves. The vigorous downwelling–upwelling patterns developing at the head and tail of each breaker are shown to generate both negative- and positive-signed energy exchange contributions in the thin sublayer underneath the water surface. The details of these exchange mechanisms are thoroughly discussed in this paper, together with the interplay between three-dimensional small-scale breaking associated with turbulence and the dominant two-dimensional wave motion. A conditional zonal analysis is proposed for the first time to understand the transient mechanisms of turbulent kinetic energy production, decay, diffusion and transport and their dependence and/or impact on surface wrinkling over the entire breaking process. The simulations provide a thorough picture of air–liquid coherent structures that develop over the breaking process, and link them to the transient mechanisms responsible for their local incidence.

Wave-driven currents and vortex dynamics on barred beaches

2001 ◽  
Vol 449 ◽  
pp. 313-339 ◽  
Author(s):  
OLIVER BÜHLER ◽  
TIVON E. JACOBSON
Keyword(s):  
Shallow Water ◽  
Shallow Water Equations ◽  
Water Waves ◽  
Wave Breaking ◽  
Bottom Topography ◽  
Breaking Waves ◽  
Vortex Structures ◽  
Water Model ◽  
Mean Flow ◽  
The Mean

We present a theoretical and numerical investigation of longshore currents driven by breaking waves on beaches, especially barred beaches. The novel feature considered here is that the wave envelope is allowed to vary in the alongshore direction, which leads to the generation of strong dipolar vortex structures where the waves are breaking. The nonlinear evolution of these vortex structures is studied in detail using a simple analytical theory to model the effect of a sloping beach. One of our findings is that the vortex evolution provides a robust mechanism through which the preferred location of the longshore current can move shorewards from the location of wave breaking. Such current dislocation is an often-observed (but ill-understood) phenomenon on real barred beaches.To underpin our results, we present a comprehensive theoretical description of the relevant wave–mean interaction theory in the context of a shallow-water model for the beach. Therein we link the radiation-stress theory of Longuet-Higgins & Stewart to recently established results concerning the mean vorticity generation due to breaking waves. This leads to detailed results for the entire life-cycle of the mean-flow vortex evolution, from its initial generation by wave breaking until its eventual dissipative decay due to bottom friction.In order to test and illustrate our theory we also present idealized nonlinear numerical simulations of both waves and vortices using the full shallow-water equations with bottom topography. In these simulations wave breaking occurs through shock formation of the shallow-water waves. We note that because the shallow-water equations also describe the two-dimensional flow of a homentropic perfect gas, our theoretical and numerical results can also be applied to nonlinear acoustics and sound–vortex interactions.

scholarly journals REPRODUCTION MODELS OF BEACH CHANGE BY STORM WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 115
Author(s):  
Masahiro Ito ◽  
Yoshito Tsuchiya
Keyword(s):  
Grain Size ◽  
Model Test ◽  
Irregular Waves ◽  
Scale Model ◽  
Regular Waves ◽  
Wave Duration ◽  
Storm Waves ◽  
The Mean ◽  
Wave Properties ◽  
Sand Grain Size

This paper presents a technique to reproduce, by a twodimensional moveable-bed model, beach change due to the timedependent storm waves which are generated by the passage of an atmospheric depression. In the model test, scaling conditions for sand grain-size, vertical and horizontal lengths, and wave height and period characteristics were established by applying the authors' scale-model relationship which was reported; and wave duration time also was decided. A method of employing regular waves in the model to represent irregular waves in the field is proposed. From the results, it was shown that the model can reproduce well the beach change in the field using the regular waves having the mean wave properties in the irregular waves.

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