Reflection and Transmission of Ship Waves by Floating Barriers

2003 ◽  
Vol 125 (1) ◽  
pp. 54-58
Author(s):  
Quan-Ming Miao ◽  
Allen T. Chwang
Keyword(s):  
Free Surface ◽  
Energy Density ◽  
Wave Energy ◽  
Outer Region ◽  
Wave Pattern ◽  
Transmission Performance ◽  
Reflection And Transmission ◽  
Ship Waves ◽  
Wave Energy Density

The reflection and transmission of ship waves by vertical floating barriers located on both sides of a fairway are investigated by the modified Dawson’s method in this paper. The free surface is specially treated to take into account the floating barriers. The wave pattern and the wave energy density between and outside the barriers are obtained. It is found that the reflection and transmission performance of a barrier is associated with its width and height. For a wider or higher barrier, more ship waves are reflected by it. A vertical floating barrier with a reasonable width and height can reduce ship waves in the outer region very efficiently.

Reflection and Transmission of Ship Waves by Floating Barriers

2002 ◽  
Author(s):  
Quan-Ming Miao ◽  
Allen T. Chwang
Keyword(s):  
Free Surface ◽  
Energy Density ◽  
Wave Energy ◽  
Outer Region ◽  
Wave Pattern ◽  
Transmission Performance ◽  
Reflection And Transmission ◽  
Ship Waves ◽  
Wave Energy Density

The reflection and transmission of ship waves by vertical floating barriers located on both sides of a fairway are investigated by the modified Dawson’s method in this paper. The free surface is specially treated to take into account the floating barriers. The wave pattern and the wave energy density between and outside the barriers are obtained. It is found that the reflection and transmission performance of a barrier is associated with its width and height. For a wider or higher barrier, more ship waves are reflected by it. A vertical floating barrier with a reasonable width and height can reduce ship waves in the outer region very efficiently.

From Bulbous Bow to Free-Surface Shock Wave—Trends of 20 Years’ Research on Ship Waves at the Tokyo University Tank

1981 ◽  
Vol 25 (03) ◽  
pp. 147-180
Author(s):  
Takao Inui
Keyword(s):  
Shock Wave ◽  
Free Surface ◽  
Field Measurements ◽  
Wave Pattern ◽  
Ship Waves ◽  
Second Stage ◽  
Initial Stage ◽  
Man And Nature ◽  
Bulbous Bow ◽  
The Relationship

Trends of 20 years' research on ship waves at the Tokyo University Tank since 1960 are briefly sketched. Stress is focused on the importance of dialogues between man and nature. The process of these dialogues is exemplified by some typical cases, including the development of bulbous bows and the finding of free-surface shock waves. Wave-pattern pictures are shown to be indispensable for the initial stage of the di alogues, while wave contours and velocity-field measurements serve well in the second stage. The current wave analysis and wake survey may be the third. The relationship between "wavebreaking" and the "free-surface shock wave" is also discussed.

A drift of Langmuir waves in a magnetized inhomogeneous plasma

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
Vasily I. Erofeev
Keyword(s):  
Energy Density ◽  
Plasma Physics ◽  
Wave Energy ◽  
Inhomogeneous Plasma ◽  
Magnetized Plasma ◽  
Plasma Inhomogeneity ◽  
Langmuir Waves ◽  
Plasma Kinetics ◽  
Nonlinear Plasma ◽  
Wave Energy Density

The concept of informativeness of nonlinear plasma physics scenarios is explained. Natural ideas of developing highly informative models of plasma kinetics are spelled out. They are applied to develop a formula that governs the drift of long Langmuir waves in spatial positions and wave vectors in a magnetized plasma due to the plasma inhomogeneity. Together with previous findings (Erofeev, Phys. Plasmas, vol. 22, 2015, 092302), the formula evidences the need for an intelligent generalization of the notion of wave energy density from usual homogeneous plasmas to inhomogeneous ones.

scholarly journals Seasonal and nightly variations of gravity-wave energy density in the middle atmosphere measured by the Purple Crow Lidar

2007 ◽  
Vol 25 (10) ◽  
pp. 2139-2145 ◽  
Author(s):  
R. J. Sica ◽  
P. S. Argall
Keyword(s):  
Energy Density ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Energy ◽  
Numerical Models ◽  
Spatial Scales ◽  
Density Fluctuations ◽  
Kinetic Energy Density ◽  
Large Power ◽  
Wave Energy Density

Abstract. The Purple Crow Lidar (PCL) is a large power-aperture product monostatic Rayleigh-Raman-Sodium-resonance-fluorescence lidar, which has been in operation at the Delaware Observatory (42.9° N, 81.4° W, 237 m elevation) near the campus of The University of Western Ontario since 1992. Kinetic-energy density has been calculated from the Rayleigh-scatter system measurements of density fluctuations at temporal-spatial scales relevant for gravity waves, e.g. soundings at 288 m height resolution and 9 min temporal resolution in the upper stratosphere and mesosphere. The seasonal averages from 10 years of measurements show in all seasons some loss of gravity-wave energy in the upper stratosphere. During the equinox periods and summer the measurements are consistent with gravity waves growing in height with little saturation, in agreement with the classic picture of the variations in the height at which gravity waves break given by Lindzen (1981). The mean values compare favourably to previous measurements when computed as nightly averages, but the high temporal-spatial resolution measurements show considerable day-to-day variability. The variability over a night is often extremely large, with typical RMS fluctuations of 50 to 100% at all heights and seasons common. These measurements imply that using a daily or nightly-averaged gravity-wave energy density in numerical models may be highly unrealistic.

Time-reverse imaging with limited S-wave velocity model information

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. MA33-MA40 ◽  
Author(s):  
Brian Steiner ◽  
Erik H. Saenger ◽  
Stefan M. Schmalholz
Keyword(s):  
Energy Density ◽  
Wave Velocity ◽  
Wave Energy ◽  
Velocity Model ◽  
Body Waves ◽  
P Wave ◽  
S Wave ◽  
Velocity Models ◽  
Wave Energy Density ◽  
Wavefield Extrapolation

Time-reverse imaging is a wave propagation algorithm for locating sources. Signals recorded by synchronized receivers are reversed in time and propagated back to the source location by elastic wavefield extrapolation. Elastic wavefield extrapolation requires a P-wave as well as an S-wave velocity model. The velocity models available from standard reflection seismic methods are usually restricted to only P-waves. In this study, we use synthetically produced time signals to investigate the accuracy of seismic source localization by means of time-reverse imaging with the correct P-wave and a perturbed S-wave velocity model. The studies reveal that perturbed S-wave velocity models strongly influence the intensity and position of the focus. Imaging the results with the individual maximum energy density for both body wave types instead of mixed modes allows individual analysis of the two body waves. P-wave energy density images render stable focuses in case of a correct P-wave and incorrect S-wave velocity model. Thus, P-wave energy density seems to be a more suitable imaging condition in case of a high degree of uncertainty in the S-wave velocity model.

Nonlinear Ship Waves at Low Froude Number

1989 ◽  
Vol 33 (03) ◽  
pp. 176-193
Author(s):  
A. J. Hermans ◽  
F. J. Brandsma
Keyword(s):  
Free Surface ◽  
Froude Number ◽  
Continuous Dependence ◽  
Wave Pattern ◽  
Ray Method ◽  
Ship Waves ◽  
Asymptotic Evaluation ◽  
Low Froude Number ◽  
Field Wave

The wave pattern of a thick ship-like object with finite bow and stern angles 0 <β<π/2 is studied. The completely blunt form p = π/2 is excluded. It turns out that the wave pattern is strongly influenced by the nonlinear terms at the free surface. The wave pattern is determined by means of the ray method. The rays are generated mainly at the bow and the stern. A crucial step is the determination of the so-called excitation coefficients. They are constructed by means of an asymptotic evaluation of a distribution of "local"sources at the free surface. It is shown that for small angles β<< 1 the excitation coefficients are the same as the ones obtained by means of an asymptotic expansion for small values of the Froude number of the results of Michell's thin-ship theory. For increasing values of β, the excitation coefficients change asymptotically. The theory herein shows a continuous dependence, nevertheless. Similar changes are observed in the far-field wave pattern.

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