On the form of the highest progressive and standing waves in deep water

1973 ◽  
Vol 331 (1587) ◽  
pp. 445-456 ◽  
Keyword(s):  
Free Surface ◽  
Numerical Integration ◽  
Gravity Wave ◽  
Standing Wave ◽  
Deep Water ◽  
Standing Waves ◽  
Infinite Depth ◽  
Single Term

The form of a progressive gravity wave on deep water, which generally must be found by numerical integration (Michell 1893) is shown to be approximated with remarkable accuracy by a single term. Six consecutive waves are transformed conformally so as to surround the point corresponding to infinite depth. The free surface then corresponds closely to the boundary of a hexagon. In a similar way the profile of a standing wave is closely approximated to by transforming four consecutive waves conformally and taking the profile as the boundary of a square. The profile agrees closely with that calculated by Penney & Price (1952) and with the experiments of Taylor (1953).

scholarly journals The set-down and set-up of directionally spread and crossing surface gravity wave groups

2017 ◽  
Vol 835 ◽  
pp. 131-169 ◽  
Author(s):  
M. L. McAllister ◽  
T. A. A. Adcock ◽  
P. H. Taylor ◽  
T. S. van den Bremer
Keyword(s):  
Free Surface ◽  
Gravity Wave ◽  
Standing Wave ◽  
Wave Pattern ◽  
Surface Gravity ◽  
Linear Wave ◽  
Surface Gravity Wave ◽  
Wave Groups ◽  
Single Wave ◽  
Set Up

For sufficiently directionally spread surface gravity wave groups, the set-down of the wave-averaged free surface, first described by Longuet-Higgins and Stewart (J. Fluid Mech. vol. 13, 1962, pp. 481–504), can turn into a set-up. Using a multiple-scale expansion for two crossing wave groups, we examine the structure and magnitude of this wave-averaged set-up, which is part of a crossing wave pattern that behaves as a modulated partial standing wave: in space, it consists of a rapidly varying standing-wave pattern slowly modulated by the product of the envelopes of the two groups; in time, it grows and decays on the slow time scale associated with the translation of the groups. Whether this crossing wave pattern actually enhances the surface elevation at the point of focus depends on the phases of the linear wave groups, unlike the set-down, which is always negative and inherits the spatial structure of the underlying envelope(s). We present detailed laboratory measurements of the wave-averaged free surface, examining both single wave groups, varying the degree of spreading from small to very large, and the interaction between two wave groups, varying both the degree of spreading and the crossing angle between the groups. In both cases, we find good agreement between the experiments, our simple expressions for the set-down and set-up, and existing second-order theory based on the component-by-component interaction of individual waves with different frequencies and directions. We predict and observe a set-up for wave groups with a Gaussian angular amplitude distribution with standard deviations of above $30{-}40^{\circ }$ ($21{-}28^{\circ }$ for energy spectra), which is relatively large for realistic sea states, and for crossing sea states with angles of separation of $50{-}70^{\circ }$ and above, which are known to occur in the ocean.

scholarly journals Different forms for nonlinear standing waves in deep water

1994 ◽  
Vol 272 ◽  
pp. 135-156 ◽  
Author(s):  
Peter J. Bryant ◽  
Michael Stiassnie
Keyword(s):  
Standing Wave ◽  
Deep Water ◽  
Nonlinear Boundary ◽  
Standing Waves ◽  
Linear Instability ◽  
Multiple Forms ◽  
Local Maxima ◽  
Progressive Waves ◽  
The Stability ◽  
Nonlinear Standing Waves

Multiple forms for standing waves in deep water periodic in both space and time are obtained analytically as solutions of Zakharov's equation and its modification, and investigated computationally as irrotational two-dimensional solutions of the full nonlinear boundary value problem. The different forms are based on weak nonlinear interactions between the fundamental harmonic and the resonating harmonics of 2, 3,…times the frequency and 4, 9,…respectively times the wavenumber. The new forms of standing waves have amplitudes with local maxima at the resonating harmonics, unlike the classical (Stokes) standing wave which is dominated by the fundamental harmonic. The stability of the new standing waves is investigated for small to moderate wave energies by numerical computation of their evolution, starting from the standing wave solution whose only initial disturbance is the numerical error. The instability of the Stokes standing wave to sideband disturbances is demonstrated first, by showing the evolution into cyclic recurrence that occurs when a set of nine equal Stokes standing waves is perturbed by a standing wave of a length equal to the total length of the nine waves. The cyclic recurrence is similar to that observed in the well-known linear instability and sideband modulation of Stokes progressive waves, and is also similar to that resulting from the evolution of the new standing waves in which the first and ninth harmonics are dominant. The new standing waves are only marginally unstable at small to moderate wave energies, with harmonics which remain near their initial amplitudes and phases for typically 100–1000 wave periods before evolving into slowly modulated oscillations or diverging.

scholarly journals LIMITING CONDITION FOR STANDING WAVE THEORIES BY PERTURBATION METHOD

1970 ◽  
Vol 1 (12) ◽  
pp. 32 ◽  
Author(s):  
Yoshito Tsuchiya ◽  
Masataka Yamaguchi
Keyword(s):  
Free Surface ◽  
Perturbation Method ◽  
Standing Wave ◽  
Vertical Wall ◽  
Standing Waves ◽  
Finite Amplitude ◽  
Surface Conditions ◽  
Wave Pressure ◽  
Wave Characteristics ◽  
Limiting Condition

The purpose of this paper is to make clear the validity and limiting condition for the application of the finite amplitude standing wave theories by the perturbation method In a numerical example, the errors of each order solution of these theories for two non-linear free surface conditions are computed for various kinds of wave characteristics and compared with each other Some experiments on the wave pressure on a vertical wall by standing waves were carried out and a plot of the limiting condition for the application of these theories is proposed based on the comparison with theoretical curves In addition, as an example of the application of these theories, the change of characteristics of wave pressure of standing waves accompanying the overtopping wave on a vertical wall is discussed.

scholarly journals Bound Coherent Structures Propagating on the Free Surface of Deep Water

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 115
Author(s):  
Dmitry Kachulin ◽  
Sergey Dremov ◽  
Alexander Dyachenko
Keyword(s):  
Free Surface ◽  
Deep Water ◽  
Coherent Structures ◽  
Water Waves ◽  
Nonlinear Models ◽  
Ideal Incompressible Fluid ◽  
Equation Model ◽  
System Of Nonlinear Equations ◽  
Potential Flows ◽  
Deep Water Waves

This article presents a study of bound periodically oscillating coherent structures arising on the free surface of deep water. Such structures resemble the well known bi-soliton solution of the nonlinear Schrödinger equation. The research was carried out in the super-compact Dyachenko-Zakharov equation model for unidirectional deep water waves and the full system of nonlinear equations for potential flows of an ideal incompressible fluid written in conformal variables. The special numerical algorithm that includes a damping procedure of radiation and velocity adjusting was used for obtaining such bound structures. The results showed that in both nonlinear models for deep water waves after the damping is turned off, a periodically oscillating bound structure remains on the fluid surface and propagates stably over hundreds of thousands of characteristic wave periods without losing energy.

Effective Power and Speed Loss of Underwater Vehicles in Close Proximity to Regular Waves

2017 ◽  
Author(s):  
Stefan Daum ◽  
Martin Greve ◽  
Renato Skejic
Keyword(s):  
Free Surface ◽  
Deep Water ◽  
Water Waves ◽  
Underwater Vehicles ◽  
Total Resistance ◽  
Wave Load ◽  
Regular Waves ◽  
Effective Power ◽  
Close Proximity ◽  
Deep Water Waves

The present study is focused on performance issues of underwater vehicles near the free surface and gives insight into the analysis of a speed loss in regular deep water waves. Predictions of the speed loss are based on the evaluation of the total resistance and effective power in calm water and preselected regular wave fields w.r.t. the non-dimensional wave to body length ratio. It has been assumed that the water is sufficiently deep and that the vehicle is operating in a range of small to moderate Froude numbers by moving forward on a straight-line course with a defined encounter angle of incident regular waves. A modified version of the Doctors & Days [1] method as presented in Skejic and Jullumstrø [2] is used for the determination of the total resistance and consequently the effective power. In particular, the wave-making resistance is estimated by using different approaches covering simplified methods, i.e. Michell’s thin ship theory with the inclusion of viscosity effects Tuck [3] and Lazauskas [4] as well as boundary element methods, i.e. 3D Rankine source calculations according to Hess and Smith [5]. These methods are based on the linear potential fluid flow and are compared to fully viscous finite volume methods for selected geometries. The wave resistance models are verified and validated by published data of a prolate spheroid and one appropriate axisymmetric submarine model. Added resistance in regular deep water waves is obtained through evaluation of the surge mean second-order wave load. For this purpose, two different theoretical models based on potential flow theory are used: Loukakis and Sclavounos [6] and Salvesen et. al. [7]. The considered theories cover the whole range of important wavelengths for an underwater vehicle advancing in close proximity to the free surface. Comparisons between the outlined wave load theories and available theoretical and experimental data were carried out for a submerged submarine and a horizontal cylinder. Finally, the effective power and speed loss are discussed from a submarine operational point of view where the mentioned parameters directly influence mission requirements in a seaway. All presented results are carried out from the perspective of accuracy and efficiency within common engineering practice. By concluding current investigations in regular waves an outlook will be drawn to the application of advancing underwater vehicles in more realistic sea conditions.

scholarly journals Instability of standing waves for non-linear Schrödinger-type equations

1988 ◽  
Vol 8 (8) ◽  
pp. 119-138 ◽  
Keyword(s):  
Dynamical Systems ◽  
Standing Wave ◽  
Optical Waveguides ◽  
Standing Waves ◽  
Positive Eigenvalue ◽  
Shooting Argument ◽  
Wave Solutions ◽  
Non Linear ◽  
Linearized Operator

AbstractA theorem is proved giving a condition under which certain standing wave solutions of non-linear Schrödinger-type equations are linearly unstable. The eigenvalue equations for the linearized operator at the standing wave can be analysed by dynamical systems methods. A positive eigenvalue is then shown to exist by means of a shooting argument in the space of Lagrangian planes. The theorem is applied to a situation arising in optical waveguides.

scholarly journals MASS TRANSPORT IN VOCOIDAL THEORY

1982 ◽  
Vol 1 (18) ◽  
pp. 22
Author(s):  
J.W. Gonsalves ◽  
D.H. Swart
Keyword(s):  
Free Surface ◽  
Mass Transport ◽  
Deep Water

The concept of mass transport is theoretically discussed within the framework provided by Vocoidal theory. The Lagrangian mass transport is divided into two parts; firstly treating the fluid as being inviscid and secondly, incorporating viscosity by means of the free surface and bottom boundaries. Eulerian mass transport is defined and is shown to correspond, in deep water, to the net flow predicted by Stokes and others.

scholarly journals Surface and internal waves in a liquid of variable depth

1969 ◽  
Vol 1 (1) ◽  
pp. 29-46 ◽  
Author(s):  
D. G. Hurley ◽  
J. Imberger
Keyword(s):  
Free Surface ◽  
Gravity Wave ◽  
Internal Waves ◽  
Infinite Number ◽  
Variable Depth ◽  
Constant Depth ◽  
Stratified Liquid

Consider a stably stratified liquid, whose density varies exponentially with the vertical co-ordinate, that is bounded above by a free surface and below by a bed whose height depends on only one of the horizontal co-ordinates. Suppose that a gravity wave, that may be either a surface or an internal one, is travelling in a direction normal to the lines of constant depth. It is shown that if the frequency is below a certain value an infinite number of waves, all of the same frequency but having differing wave lengths, are generated and expressions for their amplitude are given in terms of the changes in depth which are assumed to be small.

The semi-analytic theory of standing waves

1987 ◽  
Vol 411 (1840) ◽  
pp. 123-137 ◽  
Keyword(s):  
Numerical Calculation ◽  
Power Series ◽  
Deep Water ◽  
Standing Waves ◽  
Affirmative Answer ◽  
Rigorous Proof ◽  
Series Solutions ◽  
Wave Problem ◽  
Power Series Solutions ◽  
Formal Power

The algorithm proposed by Schwartz & Whitney ( J. Fluid Mech . 107, 147–171 (1981)) for the numerical calculation of formal power series solutions of the classical standing-wave problem is vindicated by a rigorous proof that resonances do not occur in the calculations. A detailed account of a successful algorithm is given. The analytical question of the convergence of the power series whose coefficients have been calculated remains open. An affirmative answer would be a first demonstration of the existence of standing waves on deep water.

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