An explicit Hamiltonian formulation of surface waves in water of finite depth

1992 ◽  
Vol 237 ◽  
pp. 435-455 ◽  
Author(s):  
A. C. Radder
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Hamiltonian Formulation ◽  
Vertical Plane ◽  
Finite Depth ◽  
Short Wave ◽  
Linear Dispersion ◽  
Energy Functionals ◽  
Canonical Variables ◽  
Wave Nonlinearity

A variational formulation of water waves is developed, based on the Hamiltonian theory of surface waves. An exact and unified description of the two-dimensional problem in the vertical plane is obtained in the form of a Hamiltonian functional, expressed in terms of surface quantities as canonical variables. The stability of the corresponding canonical equations can be ensured by using positive definite approximate energy functionals. While preserving full linear dispersion, the method distinguishes between short-wave nonlinearity, allowing the description of Stokes waves in deep water, and long-wave nonlinearity, applying to long waves in shallow water. Both types of nonlinearity are found necessary to describe accurately large-amplitude solitary waves.

A depth-resolved framework for the coupling of sub-surface flows and surface gravity water waves

2020 ◽  
Author(s):  
Simen Ådnøy Ellingsen ◽  
Stefan Weichert ◽  
Yan Li
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Multiple Scales ◽  
Subsurface Flow ◽  
Vertical Gradient ◽  
Finite Depth ◽  
Surface Gravity ◽  
Linear Wave ◽  
Flow Equations ◽  
Direct Integration Method

<p>This work aims to develop a new framework for the interaction of a subsurface flow and surface gravity water waves, based on a perturbation and multiple-scales expansion.  Surface waves are assumed of a narrow band δ (δ ), indicating they can be expressed as a carrier wave whose amplitude varies slowly in space and time relative to its phase. Using the Direct Integration Method proposed in Li & Ellingsen (2019), the effects of the vertical gradient of a subsurface flow are taken into account on the linear wave properties in an implicit fashion. At the second order in wave steepness ϵ, the forcing of the sub-harmonic bound waves is considered that plays a role in the primary equations for a subsurface flow.</p><p>The novel framework derives the continuity and momentum equations for a subsurface flow in two different formats, including both the depth integrated as well as the depth resolved version. The former compares with Smith (2006) to examine the roles of the rotationality of wave motions in the subsurface flow equations. The latter employs the sigma coordinate system proposed in Mellor (2003, 2008, 2015) and extends the framework therein to allow for quasi-monochromatic surface waves and the effects of the shear of a current on linear surface waves. Compared to Mellor (2003, 2008, 2015), the vertical flux/vertical radiation stress term in the proposed framework is approximated to one order of magnitude higher, i.e. O(ϵ<sup>2</sup>δ<sup>2</sup>).</p><p><strong>References</strong></p><p>Li, Y., Ellingsen, S. Å. A framework for modeling linear surface waves on shear currents in slowly varying waters. J. Geophys. Res. C: Oceans, (2019) <strong>124</strong>(4), 2527-2545.</p><p>Mellor, G. L. The three-dimensional current and surface wave equations. J. Phys. Oceanogr., (2003) <strong>33</strong>, 1978–1989.</p><p>Mellor, G. L. The depth-dependent current and wave interaction equations: a revision. J. Phys. Oceanogr., (2008) <strong>38</strong>(11), 2587-2596.</p><p>Smith, J. A. Wave–current interactions in finite depth. Journal of Physical Oceanography, (2006) <strong>36</strong>(7), 1403-1419.</p>

The scattering of surface waves by a vertical plane barrier

1969 ◽  
Vol 66 (2) ◽  
pp. 417-422 ◽  
Author(s):  
R. J. Jarvis ◽  
B. S. Taylor
Keyword(s):  
Surface Waves ◽  
Small Amplitude ◽  
Vertical Plane ◽  
Finite Depth ◽  
Infinite Depth ◽  
Plane Barrier

AbstractIn this paper we use a method due to Williams(1) to discuss the scattering of surface waves of small amplitude on water of infinite depth by a fixed vertical plane barrier extending indefinitely downwards from a finite depth.

scholarly journals Symmetry breaking in periodic and solitary gravity-capillary waves on water of finite depth

1987 ◽  
Vol 184 ◽  
pp. 183-206 ◽  
Author(s):  
Juan A. Zufiria
Keyword(s):  
Gravity Waves ◽  
Water Waves ◽  
Hamiltonian Formulation ◽  
Finite Depth ◽  
Capillary Waves ◽  
Bifurcation Structure ◽  
Low Gravity ◽  
Bifurcation Tree ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Model

A weakly nonlinear model is developed from the Hamiltonian formulation of water waves, to study the bifurcation structure of gravity-capillary waves on water of finite depth. It is found that, besides a very rich structure of symmetric solutions, non-symmetric Wilton's ripples exist. They appear via a spontaneous symmetrybreaking bifurcation from symmetric solutions. The bifurcation tree is similar to that for gravity waves. The solitary wave with surface tension is studied with the same model close to a critical depth. It is found that the solution is not unique, and that further non-symmetric solitary waves are possible. The bifurcation tree has the same structure as for the case of periodic waves. The possibility of checking these results in low-gravity experiments is postulated.

Water Waves Over a Channel of Finite Depth With a Submerged Plane Barrier

1950 ◽  
Vol 2 ◽  
pp. 210-222 ◽  
Author(s):  
Albert E. Heins
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Finite Depth ◽  
The Third ◽  
Plane Barrier

This is the third in a series of problems in the study of surface waves which have been disturbed by the presence of a plane barrier and to which a solution may be provided. We assume as in part I, that the fluid is incompressible and non-viscous, and that motion is irrotational.

On the radiation and scattering of short surface waves. Part 2

1973 ◽  
Vol 59 (1) ◽  
pp. 129-146 ◽  
Author(s):  
F. G. Leppington
Keyword(s):  
Surface Waves ◽  
Simple Wave ◽  
Finite Depth ◽  
Short Wave ◽  
Asymptotic Estimates ◽  
Radiation Problem ◽  
Expansion Technique ◽  
Wave Trains ◽  
Intersection Points ◽  
Scattering And Radiation

A short-wave asymptotic analysis is undertaken for problems concerned with the radiation and scattering of surface waves by a cylinder whose cross-section S intersects the free surface normally. It is assumed that S is locally smooth and convex at the two intersection points with the fluid, which may be of infinite or finite depth. For both the scattering and radiation problem, a matched expansion technique is used to provide asymptotic estimates, in terms of relatively simple wave-free limit potentials, for the amplitudes of the surface wave trains that propagate from S. Explicit details are given for some particular geometries, confirming and extending earlier results. The method can, in principle, be extended to deal with other geometries.

On the forced surface waves due to a vertical wave-maker in the presence of surface tension

1971 ◽  
Vol 70 (2) ◽  
pp. 323-337 ◽  
Author(s):  
P. F. Rhodes-Robinson
Keyword(s):  
Surface Tension ◽  
Surface Waves ◽  
Wave Motion ◽  
Velocity Potential ◽  
Vertical Plane ◽  
Finite Depth ◽  
Cylindrical Wave ◽  
Constant Depth ◽  
Classical Wave ◽  
Wave Maker

AbstractThe classical wave-maker problem to determine the forced two-dimensional wave motion with outgoing surface waves at infinity generated by a harmonically oscillating vertical plane wave-maker immersed in water was solved long ago by Sir Thomas Havelock. In this paper we reinvestigate the problem, making allowance for the presence of surface tension which was excluded before, and obtain a solution of the boundary-value problem for the velocity potential which is made unique by prescribing the free surface slope at the wave-maker. The cases of both infinite and finite constant depth are treated, and it is essential to employ a method which is new to this problem since the theory of Havelock cannot be extended in the latter case of finite depth. The solution of the corresponding problem concerning the axisymmetric wave motion due to a vertical cylindrical wave-maker is deduced in conclusion.

DISPERSION IN SEISMIC SURFACE WAVES

Geophysics ◽  
1951 ◽  
Vol 16 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Milton B. Dobrin
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Seismic Refraction ◽  
Wave Theory ◽  
Wave Dispersion ◽  
Surface Zone ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Arrival Times ◽  
Ground Roll

A non‐mathematical summary is presented of the published theories and observations on dispersion, i.e., variation of velocity with frequency, in surface waves from earthquakes and in waterborne waves from shallow‐water explosions. Two further instances are cited in which dispersion theory has been used in analyzing seismic data. In the seismic refraction survey of Bikini Atoll, information on the first 400 feet of sediments below the lagoon bottom could not be obtained from ground wave first arrival times because shot‐detector distances were too great. Dispersion in the water waves, however, gave data on speed variations in the bottom sediments which made possible inferences on the recent geological history of the atoll. Recent systematic observations on ground roll from explosions in shot holes have shown dispersion in the surface waves which is similar in many ways to that observed in Rayleigh waves from distant earthquakes. Classical wave theory attributes Rayleigh wave dispersion to the modification of the waves by a surface layer. In the case of earthquakes, this layer is the earth’s crust. In the case of waves from shot‐holes, it is the low‐speed weathered zone. A comparison of observed ground roll dispersion with theory shows qualitative agreement, but it brings out discrepancies attributable to the fact that neither the theory for liquids nor for conventional solids applies exactly to unconsolidated near‐surface rocks. Additional experimental and theoretical study of this type of surface wave dispersion may provide useful information on the properties of the surface zone and add to our knowledge of the mechanism by which ground roll is generated in seismic shooting.

On the modulation of water waves on shear flows

1976 ◽  
Vol 347 (1651) ◽  
pp. 537-546 ◽  
Keyword(s):  
Water Waves ◽  
Multiple Scales ◽  
Method Of Multiple Scales ◽  
Vries Equation ◽  
Harmonic Wave ◽  
Short Wave ◽  
Long Wave ◽  
Stokes Waves ◽  
The Stability ◽  
Wave Limit

The method of multiple scales is used to examine the slow modulation of a harmonic wave moving over the surface of a two dimensional channel. The flow is assumed inviscid and incompressible, but the basic flow takes the form of an arbitrary shear. The appropriate nonlinear Schrödinger equation is derived with coefficients that depend, in a complicated way, on the shear. It is shown that this equation agrees with previous work for the case of no shear; it also agrees in the long wave limit with the appropriate short wave limit of the Korteweg-de Vries equation, the shear being arbitrary. Finally, it is remarked that the stability of Stokes waves over any shear can be examined by using the results derived here.

Theory of Short Wave Excitation

1986 ◽  
Vol 30 (03) ◽  
pp. 147-152
Author(s):  
Yong Kwun Chung
Keyword(s):  
Incident Wave ◽  
Characteristic Length ◽  
Finite Depth ◽  
Short Wave ◽  
The Body ◽  
Wave Number ◽  
Floating Body ◽  
Wave Excitation ◽  
Exciting Forces ◽  
Wave Exciting Forces

When the wavelength of the incident wave is short, the total surface potential on a floating body is found to be 2∅ i & O (m-l∅ i) on the lit surface and O (m-l∅ j) on the shadow surface where ~b i is the potential of the incident wave and m the wave number in water of finite depth. The present approximation for wave exciting forces and moments is reasonably good up to X/L ∅ 1 where h is the wavelength and L the characteristic length of the body.

Uniformly travelling water waves from a dynamical systems viewpoint: some insights into bifurcations from Stokes’ family

1992 ◽  
Vol 241 ◽  
pp. 333-347 ◽  
Author(s):  
C. Baesens ◽  
R. S. Mackay
Keyword(s):  
Gravity Waves ◽  
Water Waves ◽  
Travelling Waves ◽  
Hamiltonian Formulation ◽  
Inviscid Fluid ◽  
Centre Manifold ◽  
Numerical Work ◽  
Bifurcation Tree ◽  
Area Preserving

Numerical work of many people on the bifurcations of uniformly travelling water waves (two-dimensional irrotational gravity waves on inviscid fluid of infinite depth) suggests that uniformly travelling water waves have a reversible Hamiltonian formulation, where the role of time is played by horizontal position in the wave frame. In this paper such a formulation is presented. Based on this viewpoint, some insights are given into bifurcations from Stokes’ family of periodic waves. It is demonstrated numerically that there is a ‘fold point’ at amplitude A0 ≈ 0.40222. Assuming non-degeneracy of the fold and existence of an associated centre manifold, this explains why a sequence of p/q-bifurcations occurs on one side of A0, with 0 < p/q [les ] ½, in the order of the rationals. Secondly, it explains why no symmetry-breaking bifurcation is observed at A0, contrary to the expectations of some. Thirdly, it explains why the bifurcation tree for periodic uniformly travelling waves looks so much like that for the area-preserving Hénon map. Fourthly, it leads to predictions of a rich variety of spatially quasi-periodic, heteroclinic and chaotic waves.

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