Interaction of Water Waves and Currents
TL;DR: In this article, the authors discuss the varied physical circumstances in which interactions among water waves and currents occur and different mathematical approaches, relevant observations, and experiments that are applicable to all or some of these physical circumstances are described.
Abstract: Publisher Summary This chapter discusses the varied physical circumstances in which interactions among water waves and currents occur. Different mathematical approaches, relevant observations, and experiments that are applicable to all or some of these physical circumstances are described. The emphasis is on waves and their interaction with preexisting currents rather than on wave-generated currents. Common simplifying assumption is that the waves are of sufficiently small amplitude for the free-surface boundary conditions to be linearized and evaluated at, or close to, the mean free surface. Most progress can be made in this subject with such a constraint, but wherever possible, finite-amplitude effects are discussed. Unlike some other common forms of wave motion, water waves involve water motion varying with direction perpendicular to the space in which they propagate. The chapter concludes on the interaction of waves generated by a ship with the flow around it.
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28 Dec 1987
TL;DR: Tidal Patterns Meteorological and Other Non-tidal Disturbances Some Definitions of Common Terms Basic Statistics of Tides as Time Series Observations and Data Reduction Forces Analysis and Prediction Tidal Dynamics Biology: Some Tidal Influences Filters for Tidal Time Series Response Analysis Inputs and Theory Analysis of Currents Theoretical Tidal dynamics Legal Definitions in the Coastal Zone as discussed by the authors.
Abstract: Introduction: Early Ideas and Observations Tidal Patterns Meteorological and Other Non-tidal Disturbances Some Definitions of Common Terms Basic Statistics of Tides as Time Series Observations and Data Reduction Forces Analysis and Prediction Tidal Dynamics Biology: Some Tidal Influences Filters for Tidal Time Series Response Analysis Inputs and Theory Analysis of Currents Theoretical Tidal Dynamics Legal Definitions in the Coastal Zone
987 citations
Cites background from "Interaction of Water Waves and Curr..."
...Currents can also affect the direction and propagation of a wave train, but the most significant interaction between waves and currents occurs when they are opposed to each other (Peregrine, 1976)....
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TL;DR: A review of physical mechanisms of the rogue wave phenomenon is given in this article, where the authors demonstrate that freak waves may appear in deep and shallow waters and demonstrate that these mechanisms remain valid but should be modified.
Abstract: A review of physical mechanisms of the rogue wave phenomenon is given. The data of marine observations as well as laboratory experiments are briefly discussed. They demonstrate that freak waves may appear in deep and shallow waters. Simple statistical analysis of the rogue wave probability based on the assumption of a Gaussian wave field is reproduced. In the context of water wave theories the probabilistic approach shows that numerical simulations of freak waves should be made for very long times on large spatial domains and large number of realizations. As linear models of freak waves the following mechanisms are considered: dispersion enhancement of transient wave groups, geometrical focusing in basins of variable depth, and wave-current interaction. Taking into account nonlinearity of the water waves, these mechanisms remain valid but should be modified. Also, the influence of the nonlinear modulational instability (Benjamin–Feir instability) on the rogue wave occurence is discussed. Specific numerical simulations were performed in the framework of classical nonlinear evolution equations: the nonlinear Schrodinger equation, the Davey–Stewartson system, the Korteweg–de Vries equation, the Kadomtsev–Petviashvili equation, the Zakharov equation, and the fully nonlinear potential equations. Their results show the main features of the physical mechanisms of rogue wave phenomenon.
962 citations
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...Noting that rogue waves were observed very often in such strong currents as Gulf Stream and Agulhas Current, the of the wave-current interaction requires a special investigation [42,3,4,43,27,28]....
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...Noting that rogue waves were observed very often in such strong currents as Gulf Stream and Agulhas Current, the problem of the wave-current interaction requires a special investigation (Peregrine, 1976; Lavrenov, 1998a,b; White & Fornberg, 1998; Brown, 2000, 2001)....
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Book•
01 Feb 2010TL;DR: The SWAN wave model as discussed by the authors is a wave model based on linear wave theory (SWAN) for oceanic and coastal waters, and it has been shown to be effective in detecting ocean waves.
Abstract: 1. Introduction 2. Observation techniques 3. Description of ocean waves 4. Statistics 5. Linear wave theory (oceanic waters) 6. Waves in oceanic waters 7. Linear wave theory (coastal waters) 8. Waves in coastal waters 9. The SWAN wave model Appendices References Index.
874 citations
TL;DR: In this paper, the authors introduce the concept of rogue waves, which is the name given by oceanographers to isolated large amplitude waves, that occur more frequently than expected for normal, Gaussian distributed, statistical events.
851 citations
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...The current changes the dispersion relation and may refract waves to converge in a single point creating a large amplitude wave (see [152] for an old but good review on the interaction of waves and current; more recent papers on the subject are [153,154,2,155–157])....
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TL;DR: In most circumstances, the properties of rogue waves and their probability of occurrence appear to be consistent with second-order random-wave theory as mentioned in this paper, although it is unclear whether these represent measurement errors or statistical flukes, or are caused by physical mechanisms not covered by the model.
Abstract: Oceanic rogue waves are surface gravity waves whose wave heights are much larger than expected for the sea state. The common operational definition requires them to be at least twice as large as the significant wave height. In most circumstances, the properties of rogue waves and their probability of occurrence appear to be consistent with second-order random-wave theory. There are exceptions, although it is unclear whether these represent measurement errors or statistical flukes, or are caused by physical mechanisms not covered by the model. A clear deviation from second-order theory occurs in numerical simulations and wave-tank experiments, in which a higher frequency of occurrence of rogue waves is found in long-crested waves owing to a nonlinear instability.
777 citations
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2,697 citations
TL;DR: The radiation stresses in water waves play an important role in a variety of oceanographic phenomena, for example in the change in mean sea level due to storm waves (wave set-up), the generation of "surf-beats", the interaction of waves with steady currents, and the steepening of short gravity waves on the crests of longer waves as discussed by the authors.
1,567 citations
TL;DR: In this article, a general theory of mass transport is developed, which takes account of the viscosity, and leads to results in agreement with observation, and is shown that the nature of the motion in the interior depends upon the ratio of the wave amplitude a to the thickness δ of the boundary layer.
Abstract: It was shown by Stokes that in a water wave the particles of fluid possess, apart from their orbital motion, a steady second-order drift velocity (usually called the mass-transport velocity). Recent experiments, however, have indicated that the mass-transport velocity can be very different from that predicted by Stokes on the assumption of a perfect, non-viscous fluid. In this paper a general theory of mass transport is developed, which takes account of the viscosity, and leads to results in agreement with observation. Part I deals especially with the interior of the fluid. It is shown that the nature of the motion in the interior depends upon the ratio of the wave amplitude a to the thickness $\delta $ of the boundary layer: when a$^{2}$/$\delta ^{2}$ is small the diffusion of vorticity takes place by viscous 'conduction'; when a$^{2}$/$\delta ^{2}$ is large, by convection with the mass-transport velocity. Appropriate field equations for the stream function of the mass transport are derived. The boundary layers, however, require separate consideration. In part II special attention is given to the boundary layers, and a general theory is developed for two types of oscillating boundary: when the velocities are prescribed at the boundary, and when the stresses are prescribed. Whenever the motion is simple-harmonic the equations of motion can be integrated exactly. A general method is described for determining the mass transport throughout the fluid in the presence of an oscillating body, or with an oscillating stress at the boundary. In part III, the general method of solution described in parts I and II is applied to the cases of a progressive and a standing wave in water of uniform depth. The solutions are markedly different from the perfect-fluid solutions with irrotational motion. The chief characteristic of the progressive-wave solution is a strong forward velocity near the bottom. The predicted maximum velocity near the bottom agrees well with that observed by Bagnold.
1,186 citations