Zero wave resistance for ships moving in shallow channels at supercritical speeds

1997 ◽  
Vol 335 ◽  
pp. 305-321 ◽  
Author(s):  
XUE-NONG CHEN ◽  
SOM DEO SHARMA
Keyword(s):  
Shallow Water ◽  
Water Channel ◽  
Wave Theory ◽  
Wave Pattern ◽  
Wave Resistance ◽  
Kp Equation ◽  
Nonlinear Case ◽  
Hull Form ◽  
Ship Waves ◽  
Shallow Channel

This paper deals with the wave pattern and wave resistance of a slender ship moving steadily at supercritical speed in a shallow water channel. Using, successively, linear and nonlinear shallow-water wave theory it is demonstrated that, if the hull form is adapted to speed and channel geometry according to certain rules, the ship waves can be made to form a localized pattern around the ship that moves at the same speed as the ship and at the same time the associated wave resistance can be made to vanish. In the nonlinear case, the zero-wave-resistance ship hull is derived from a KP equation solution of the oblique interaction of two identical solitons. This astonishing phenomenon may be called shallow-channel superconductivity.

Effect of Shallow Water on a Mathematical Hull at High Subcritical and Supercritical Speeds

1986 ◽  
Vol 30 (02) ◽  
pp. 85-93
Author(s):  
A. Millward ◽  
M. G. Bevan
Keyword(s):  
Shallow Water ◽  
Wave Theory ◽  
Hull Form ◽  
Towing Tank ◽  
Resistance Peak ◽  
Good Agreement ◽  
Made In

Experiments have been made in a towing tank to measure the resistance of a mathematical hull form in deepwater and in shallow water at high subcritical and supercritical speeds. The data have been compared with calculations using linearized wave theory for the same hull shape. The results have shown fairly good agreement, with the greatest differences occurring near the subcritical resistance peak.

A slender ship moving at a near-critical speed in a shallow channel

1995 ◽  
Vol 291 ◽  
pp. 263-285 ◽  
Author(s):  
Xue-Nong Chen ◽  
Som Deo Sharma
Keyword(s):  
Numerical Procedure ◽  
Wave Theory ◽  
Wave Pattern ◽  
Slender Body Theory ◽  
Petviashvili Equation ◽  
Theoretical Predictions ◽  
Local Wave ◽  
Sinkage And Trim ◽  
Step Algorithm ◽  
Shallow Channel

The problem solved concerns a slender ship moving at a near-critical steady speed in a shallow channel, not necessarily in symmetric configuration, involving the special phenomenon of generation of solitary waves. By using the technique of matched asymptotic expansions along with nonlinear shallow-water wave theory, the problem is reduced to a Kadomtsev–Petviashvili equation in the far field, matched with a nearfield solution obtained by an improved slender-body theory, taking the local wave elevation and longitudinal disturbance velocity into account. The ship can be either fixed or free to squat. Besides wave pattern and wave resistance, the hydrodynamic lift force and trim moment are calculated by pressure integration in the fixed-hull case; running sinkage and trim, by condition of hydrodynamic equilibrium in the free-hull case. The numerical procedure for solving the KP equation consists of a finite-difference method, namely, fractional step algorithm with Crank–Nicolson-like schemes in each half step. Calculated results are compared with several published shipmodel experiments and other theoretical predictions; satisfactory agreement is demonstrated.

scholarly journals Ship waves: the calculation of wave profiles

1932 ◽  
Vol 135 (826) ◽  
pp. 1-13 ◽  
Keyword(s):  
Velocity Potential ◽  
Theoretical Calculations ◽  
Wave Pattern ◽  
Wave Resistance ◽  
Surface Elevation ◽  
Horizontal Section ◽  
Ship Waves ◽  
Local Disturbance ◽  
Surface Disturbance ◽  
Wave Profiles

1. The surface disturbance produced by a ship is usually analysed into two parts : one is called the local disturbance and the other forms the wave pattern, the supply of energy required for the second part giving rise to the wave resistance of the ship. For a direct comparison between observed and theoretical surface elevation it is necessary to calculate both parts of the disturbance. This has been carried out recently for a certain case by Mr. W. C. S. Wigley,* working at the William Froude Laboratory. The model was of uniform horizontal section and sufficiently deep to be treated as theoretically of infinite draught, while the section consisted of a triangular bow and stern connected by a straight middle body ; the surface elevation along the side of the model was observed at various speeds, and compared with the theoretical calculations. The following paper deals with the calculation of the surface elevation in cases of this type. The theory is developed here from the velocity potential of a doublet at any given depth below the free surface of the water ; this has the advantage of being capable of wide generalisation, and, moreover, the introduction of a small frictional term, which is ultimately made to vanish, keeps the expressions determinate throughout the analysis.

scholarly journals The wave pattern of a doublet in a stream

1928 ◽  
Vol 121 (788) ◽  
pp. 515-523 ◽  
Keyword(s):  
Surface Effect ◽  
Ideal Point ◽  
Finite Size ◽  
Wave Pattern ◽  
Wave Resistance ◽  
Point Of View ◽  
The Body ◽  
Surface Elevation ◽  
More Care ◽  
Forced Waves

The following paper is a study of the surface waves caused by a doublet in a uniform stream, and in particular the variation in the pattern with the velocity of the stream or the depth of the doublet. In most recent work on this subject attention has been directed more to the wave resistance, which can be evaluated with less difficulty than is involved in a detailed study of the waves; in fact, it would seem that it is not necessary for that purpose to know the surface elevation completely, but only certain significant terms at large distances from the disturbance. Recent experimental work has shown con­siderable agreement between theoretical expressions for wave resistance and results for ship models of simple form, and attempts have been made at a similar comparison for the surface elevation in the neighbourhood of the ship. In the latter respect it may be necessary to examine expressions for the surface elevation with more care, as they are not quite determinate; any suitable free disturbance may be superposed upon the forced waves. For instance, it is well known that in a frictionless liquid a possible solution is one which gives waves in advance as well as in the rear of the ship, and the practical solution is obtained by superposing free waves which annul those in advance, or by some equivalent artifice. This process is simple and definite for an ideal point disturbance, but for a body of finite size or a distributed disturbance the complete surface elevation in the neighbourhood of the body requires more careful specification as regards the local part due to each element. It had been intended to consider some expressions specially from this point of view, but as the matter stands at present it would entail a very great amount of numerical calculation, and the present paper is limited to a much simpler problem although also involving considerable computation. A horizontal doublet of given moment is at a depth f below the surface of a stream of velocity c ; the surface effect may be described as a local disturbance symmetrical fore and aft of the doublet together with waves to the rear. Two points are made in the following work.

Development and Assessment of a Total Resistance Optimized Bow for the AE 36

1994 ◽  
Vol 31 (02) ◽  
pp. 149-160
Author(s):  
Donald C. Wyatt ◽  
Peter A. Chang
Keyword(s):  
Experimental Data ◽  
Optimization Procedure ◽  
Wave Resistance ◽  
Scale Model ◽  
Optimization Approach ◽  
Nonlinear Constraints ◽  
Total Resistance ◽  
Hull Form ◽  
Final Design ◽  
Resistance Data

A numerically optimized bow design is developed to reduce the total resistance of a 23 000 ton ammunition ship (AE 36) at a speed of 22 knots. An optimization approach using slender-ship theory for the prediction of wave resistance is developed and applied. The new optimization procedure is an improvement over previous optimization methodologies in that it allows the use of nonlinear constraints which assure that the final design remains within practical limits from construction and operational perspectives. Analytic predictions indicate that the AE 36 optimized with this procedure will achieve a 40% reduction in wave resistance and a 33% reduction in total resistance at 22 knots relative to a Kracht elliptical bulb bow design. The optimization success is assessed by the analysis of 25th scale model resistance data collected at the David Taylor Research Center deepwater towing basin. The experimental data indicate that the optimized hull form yields a 51% reduction in wave resistance and a 12% reduction in total resistance for the vessel at 22 knots relative to the Kracht bulb bow design. Similarly encouraging results are also observed when comparisons are made with data collected on two other conventionally designed AE 36 designs.

Effects of Cnoidal Wave-Induced Seepage on Vertical Breakwater Resting on Permeable Elastic Seabed

2014 ◽  
Vol 716-717 ◽  
pp. 284-288
Author(s):  
Jian Kang Yang ◽  
Hua Huang ◽  
Lin Guo ◽  
Jing Rong Lin ◽  
Qing Yong Zhu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Wave Theory ◽  
Cnoidal Wave ◽  
Load Prediction ◽  
Wave Load ◽  
Seepage Pressure ◽  
Theoretical Investigations ◽  
Nonlinearity Effect ◽  
Wave Nonlinearity ◽  
Wave Induced

Theoretical investigations on cnoidal waves interacting with breakwater resting on permeable elastic seabed are presented in this paper. Based on the shallow water reflected wave theory and Biot consolidation theory on wave-induced seepage pressure, the analytical solutions to first order cnoidal wave reflection and wave-induced seepage pressure are obtained by the eigenfunction expansion approach. Numerical results are presented to show the effects of depth of water, breakwater geometry on cnoidal wave-induced seepage uplift force and overturning moment. Compared with Airy wave theory, in certain shallow water conditions, the shallow water wave theory can more effectively illustrate wave nonlinearity effect in wave load prediction.

scholarly journals Generation and Propagation of Tsunami by a Moving Realistic Curvilinear Slide Shape with Variable Velocities in Linearized Shallow-Water Wave Theory

Engineering ◽  
2010 ◽  
Vol 02 (07) ◽  
pp. 529-549 ◽  
Author(s):  
Hossam Shawky Hassan ◽  
Khaled Tawfik Ramadan ◽  
Sarwat Nageeb Hanna
Keyword(s):  
Shallow Water ◽  
Water Wave ◽  
Wave Theory ◽  
Shallow Water Wave

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.

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