Capillary-gravity waves over a sloping beach

1973 ◽  
Vol 74 (3) ◽  
pp. 539-547 ◽  
Author(s):  
D. A. Allwood
Keyword(s):  
Surface Tension ◽  
Standing Wave ◽  
Gravity Waves ◽  
Velocity Potential ◽  
Surface Tension Force ◽  
Finite Amplitude ◽  
Wave Solutions ◽  
Linearized Theory ◽  
Sloping Beach ◽  
Effect Of Surface

AbstractIt is shown how the solution for the velocity potential may be determined when the effect of surface tension is included in the linearized theory of surface waves over a sloping beach. In particular, two independent standing wave solutions are found, both of which have finite amplitude at the shoreline. The results agree with those of previous writers when the surface tension force tends to zero.

The influence of surface tension on the reflection of water waves by a plane vertical barrier

1968 ◽  
Vol 64 (3) ◽  
pp. 795-810 ◽  
Author(s):  
D. V. Evans
Keyword(s):  
Surface Tension ◽  
Water Waves ◽  
Related Problem ◽  
Velocity Potential ◽  
Surface Tension Force ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Reflected Wave ◽  
Vertical Barrier ◽  
Effect Of Surface

AbstractIn this paper the effect of surface tension is included in a well-known problem in the theory of two-dimensional infinitesimal water waves. The problem is that of the reflection of waves from a fixed vertical barrier immersed to a depth a into deep water. It is shown how the solution for the velocity potential may be determined uniquely when simple assumptions are made concerning the behaviour of the free surface near the barrier. In particular, expressions are derived for the reflection coefficient, defined as the ratio of the amplitude of the reflected wave to that of the incident wave, at infinity, and the transmission coefficient, defined similarly. It is shown how these coefficients, for small values of the surface tension force, tend to the values obtained by Ursell (4) when surface tension is ignored. The related problem of a completely immersed vertical barrier extending to a distance a from the surface may be solved in a similar manner. Expressions for the reflection and transmission coefficients for this case are given.

Capillary–gravity waves against a vertical cliff

1968 ◽  
Vol 64 (3) ◽  
pp. 827-832 ◽  
Author(s):  
B. A. Packham
Keyword(s):  
Boundary Condition ◽  
Surface Tension ◽  
Gravity Waves ◽  
Solid Boundary ◽  
Additional Boundary Condition ◽  
Additional Force ◽  
Sloping Beach ◽  
Effect Of Surface

In considering the problem of waves on a sloping beach, little regard seems to have been given to the effect of surface tension. Wehausen and Laitone (7) tend to attribute this to the fact that the additional force is small. This does not, of course, preclude the possibility that the effect may be appreciable in certain regions, and Longuet-Higgins (3), for example, has shown this to be the case near the crests for waves on the point of breaking. They also add, which is probably rather more pertinent, that difficulties arise when a solid boundary pierces the surface, since an additional boundary condition is required at the intersection, but give no indication as to what the boundary condition should be.

The effect of surface tension on the waves produced by a heaving circular cylinder

1968 ◽  
Vol 64 (3) ◽  
pp. 833-847 ◽  
Author(s):  
D. V. Evans
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Circular Cylinder ◽  
Water Waves ◽  
Wave Amplitude ◽  
Velocity Potential ◽  
Linearized Theory ◽  
The Waves ◽  
Energy Argument ◽  
Effect Of Surface

AbstractIn this paper the effect of surface tension on water waves is considered. The usual assumptions of the linearized theory are made. A uniqueness theorem is derived for the waves at infinity for a general class of bounded two-dimensional obstacles in a free surface by means of an energy argument. It is shown how the wave amplitude at infinity depends on the prescribed angle at which the free surface meets the normal to the obstacle. The particular case of a heaving half-immersed circular cylinder is considered in detail, and an expression obtained for the velocity potential in terms of a convergent infinite series, the coefficients of which may be computed.

The instabilities of gravity waves of finite amplitude in deep water I. Superharmonics

1978 ◽  
Vol 360 (1703) ◽  
pp. 471-488 ◽  
Keyword(s):  
Stream Function ◽  
Gravity Waves ◽  
Velocity Potential ◽  
Travelling Waves ◽  
Normal Modes ◽  
Phase Speed ◽  
Finite Amplitude ◽  
Fundamental Wave ◽  
Wave Steepness ◽  
Horizontal Scale

In this paper we embark on a calculation of all the normal-mode perturbations of nonlinear, irrotational gravity waves as a function of the wave steepness. The method is to use as coordinates the stream-function and velocity potential in the steady, unperturbed wave (seen in a reference frame moving with the phase speed) together with the time t. The dependent quantities are the cartesian displacements and the perturbed stream function at the free surface. To begin we investigate the ‘superharmonics’, i.e. those perturbations having the same horizontal scale as the fundamental wave, or less. When the steepness of the fundamental is small, the normal modes take the form of travelling waves superposed on the basic nonlinear wave. As the steepness increases the frequency of each perturbation tends generally to be diminished. At a steepness ak ≈ 0.436 it appears that the two lowest modes coalesce and an instability arises. There is evidence that this critical steepness corresponds precisely with the steepness at which the phase velocity is a maximum, considered as a function of ak. The calculations are facilitated by the discovery of some new identities between the coefficients in Stokes’s expansion for waves of finite amplitude.

Gravity waves with effect of surface tension and fluid viscosity

2006 ◽  
Vol 18 (3) ◽  
pp. 171-176 ◽  
Author(s):  
Xiao-Bo CHEN ◽  
Wen-Yang DUAN ◽  
Dong-Qiang LU
Keyword(s):  
Surface Tension ◽  
Gravity Waves ◽  
Fluid Viscosity ◽  
Effect Of Surface

EFFECTS OF SURFACE TENSION ON TRAPPED MODES IN A TWO-LAYER FLUID

2015 ◽  
Vol 57 (2) ◽  
pp. 189-203 ◽  
Author(s):  
S. SAHA ◽  
S. N. BORA
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Circular Cylinder ◽  
Boundary Value Problems ◽  
Finite Depth ◽  
Trapped Modes ◽  
Trapped Waves ◽  
Linearized Theory ◽  
Horizontal Circular Cylinder ◽  
Effect Of Surface

We consider a two-layer fluid of finite depth with a free surface and, in particular, the surface tension at the free surface and the interface. The usual assumptions of a linearized theory are considered. The objective of this work is to analyse the effect of surface tension on trapped modes, when a horizontal circular cylinder is submerged in either of the layers of a two-layer fluid. By setting up boundary value problems for both of the layers, we find the frequencies for which trapped waves exist. Then, we numerically analyse the effect of variation of surface tension parameters on the trapped modes, and conclude that realistic changes in surface tension do not have a significant effect on the frequencies of these.

Computation of a Propagating Interface in Multiphase Flows Using an Adaptive Coupled Level Set Method

2002 ◽  
Author(s):  
Ruquan Liang ◽  
Satoru Komori
Keyword(s):  
Surface Tension ◽  
Level Set Method ◽  
Level Set ◽  
Multiphase Flows ◽  
Surface Tension Force ◽  
Numerical Results ◽  
Passive Transport ◽  
Effect Of Surface ◽  
Good Agreement ◽  
Numerical Strategy

We present a numerical strategy for a propagating interface in multiphase flows using a level set method combined with a local mesh adaptative technique. We use the level set method to move the propagating interface in multiphase flows. We also use the local mesh adaptative technique to increase the grid resolution at regions near the propagating interface and additionally at the regions near points of high curvature with a minimum of additional expense. For illustration, we apply the adaptive coupled level set method to a collection of bubbles moving under passive transport. Good agreement has been obtained in the comparision of the numerical results for the collection of bubbles using an adaptative grid with those using a single grid. We also apply the adaptive coupled level set method to a droplet falling on a step where it is important to accurately model the effect of surface tension force and the motion of the free-surface, and the numerical results agree very closely with available data.

Capillary–gravity waves of solitary type and envelope solitons on deep water

1993 ◽  
Vol 252 ◽  
pp. 703-711 ◽  
Author(s):  
Michael S. Longuet-Higgins
Keyword(s):  
Surface Tension ◽  
Dispersion Relation ◽  
Gravity Waves ◽  
Deep Water ◽  
Small Amplitude ◽  
Finite Amplitude ◽  
Surface Slope ◽  
Carrier Wave ◽  
Envelope Solitons ◽  
Special Case

The existence of steady solitary waves on deep water was suggested on physical grounds by Longuet-Higgins (1988) and later confirmed by numerical computation (Longuet-Higgins 1989; Vanden-Broeck & Dias 1992). Their numerical methods are accurate only for waves of finite amplitude. In this paper we show that solitary capillary-gravity waves of small amplitude are in fact a special case of envelope solitons, namely those having a carrier wave of length 2π(T/ρg)1½2 (g = gravity, T = surface tension, ρ = density). The dispersion relation $c^2 = 2(1-\frac{11}{32}\alpha^2_{\max)$ between the speed c and the maximum surface slope αmax is derived from the nonlinear Schrödinger equation for deep-water solitons (Djordjevik & Redekopp 1977) and is found to provide a good asymptote for the numerical calculations.

The propagation of short surface waves on longer gravity waves

1987 ◽  
Vol 177 ◽  
pp. 293-306 ◽  
Author(s):  
M. S. Longuet-Higgins
Keyword(s):  
Gravity Waves ◽  
Wave Breaking ◽  
Surface Wind ◽  
Short Wave ◽  
Finite Amplitude ◽  
Sea Surface ◽  
Wind Drift ◽  
Method Of Calculation ◽  
Linearized Theory ◽  
The Mean

To understand the imaging of the sea surface by radar, it is useful to know the theoretical variations in the wavelength and steepness of short gravity waves propagated over the surface of a train of longer gravity waves of finite amplitude. Such variations may be calculated once the orbital accelerations and surface velocities in the longer waves have been accurately determined – a non-trivial computational task.The results show that the linearized theory used previously for the longer waves is generally inadequate. The fully nonlinear theory used here indicates that for longer waves having a steepness parameter AK = 0.4, for example, the short-wave steepness can be increased at the crests of the longer waves by a factor of order 8, compared with its value at the mean level. (Linear theory gives a factor less than 2.)The calculations so far reported are for free, irrotational gravity waves travelling in the same or directly opposite sense to the longer waves. However, the method of calculation could be extended without essential difficulty so as to include effects of surface tension, energy dissipation due to short-wave breaking, surface wind-drift currents, and to arbitrary angles of wave propagation.

Differential equations for long-period gravity waves on fluid of rapidly varying depth

1977 ◽  
Vol 83 (2) ◽  
pp. 289-310 ◽  
Author(s):  
James Hamilton
Keyword(s):  
Gravity Waves ◽  
Wave Equations ◽  
Velocity Potential ◽  
Taylor Series Expansion ◽  
Finite Amplitude ◽  
Necessary Condition ◽  
Exact Equation ◽  
Rapid Convergence ◽  
Long Period ◽  
Long Wave

The conventional long-wave equations for waves propagating over fluid of variable depth depend for their formal derivation on a Taylor series expansion of the velocity potential about the bottom. The expansion, however, is not possible if the depth is not an analytic function of the horizontal co-ordinates and it is a necessary condition for its rapid convergence that the depth is also slowly varying. We show that if in the case of two-dimensional motions the undisturbed fluid is first mapped conformally onto a uniform strip, before the Taylor expansion is made, the analytic condition is removed and the approximations implied in the lowest-order equations are much improved.In the limit of infinitesimal waves of very long period, consideration of the form of the error suggests that by modifying the coefficients of the reformulated equation we may find an equation exact for arbitrary depth profiles. We are thus able to calculate the reflexion coefficients for long-period waves incident on a step change in depth and a half-depth barrier. The forms of the coefficients of the exact equation are not simple; however, for these particular cases, comparison with the coefficients of the reformulated long-wave equation suggests that in most cases the latter may be adequate. This opens up the possibility of beginning to study finite amplitude and frequency effects on regions of rapidly varying depth.

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