THE COUNTER-JET FORMATION IN AN AIR BUBBLE INDUCED BY THE IMPACT OF SHOCK WAVES

The interaction of an air bubble (isolated in water or attached to a boundary) with shock waves induced by electric sparks is investigated by high-speed photography.The interaction is closely related to the counter-jet induced by the impact of shock waves.The formation of a counter-jet in an air bubble is related to the liquid jet formed in the same air bubble,but the mechanism is different with that of the counter-jet formation in a collapsing cavitation bubble.The formation of a counter-jet in an air bubb...     

WAVES GENERATED BY A SUBMERGED BODY MOVING IN STRATIFIED FLUIDS AND VERTICAL STRUCTURES OF INTERNAL WAVES

This dissertation deals with the internal waves generated by a submerged moving body in stratified fluids by combining theoretical and experimental methods. Our purpose is to provide some scientific evidences for non-acoustic detection of underwater moving bodies based on the principles of dynamics of the internal waves. An approach to velocity potentials obtained by superposing Green‘s functions of sources and sinks was proposed for Kelvin waves at the free surface or interface in a two-layer fluid. The effects of interacting surface and internal wave modes induced by a dipole on the surface divergence field were investigated. A new theoretical model formulating the interaction of a two dimensional submerged moving body with the conjugate flow in a three-layer fluid was established. An exact solution satisfying the two dimensional Benjamin Ono equation was obtained and the vertically propagating properties of the weakly nonlinear long waves were studied hy means of the ray theory and WKB method. The above theoretical results are qualitatively consistent with those obtained in the experiments conducted by the author.     

REFLECTION AND TRANSMISSION OF WATER WAVES BY POROUS VERTICAL PLATES

The reflection and transmission of small amplitude surface waves by two verticalporous plates with spacing L fixed in the middle of an infinitely long channel of constant depthare studied.Analytical solutions in closed forms are obtained for the surface wave profiles.It isfound that,when the spacing L is a quarter-wavelength plus a multiple of the half-wavelength ofthe incident wave,not only the reflected wave amplitude but also the transmitted wave amplitudereduce to minima.On the other hand,when the spacing L is a multiple of the half-wavelengthof the incident wave,both the reflected wave amplitude and the transmitted wave amplitude havethe maximum values.For these two special cases,the energy dissipation caused by the twoporous plates and the water between them are also discussed.     

REFLECTION OF OBLIQUE INCIDENT WAVES BY PERFORATED CAISSONS WITH TRAVERSE WALL

The interaction of oblique incident waves with infinite number of perforated caissons is investigated. The fluid domain is divided into infinite sub-domains by the caissons, and eigen-function expansion is applied to expand velocity potentials in each domain. A phase relation is introduced for wave oscillation in each caisson, and the structure geometry is considered in constructing the models of reflection waves. The reflected waves with the present analysis include all of the waves traveling in different directions when incident wave period is short. Numerical examinations show that velocities at the inner and outer sides of the front walls of caissons are close to each other, and reflection coefficients satisfy the energy conservation relation very well when porous effect parameter is infinite. Numerical results show that the reflection coefficients of oblique incident waves are smaller for shorter caissons at low frequency, and decrease with the increase of wave incident angle.     

THE INTRUSION AND INFLUENCES OF INTRASEASONAL LONG ROSSBY WAVES IN THE EAST CHINA SEA

The analysis of sea level data from tide stations and ocean general circulation model (OGCM) shows that the intraseasonal long Rossby wave results in the intraseasonal variations of Kuroshio axis and transport in the upper reaches of the Kuroshio in the East China Sea (ECS). Due to the transport modulation induced by Ryukyu Islands, the intraseasonal variation is very weak in the lower reaches of the Kuroshio in the ECS. A two-layer model reveals the relation among Kuroshio frontal unstable wave with topography,transport and the axis position of the Kuroshio, from which we can infer that the intrusion of intraseasonal long Rosshy wave may stimulate the Kuroshio frontal unstable wave in the upper reaches of the Kuroshio in the ECS. The altimeter data also shows that the sea level anomaly resulting from intraseasonal long Rossby wave could pass the channel between Taiwan and Ryukyu Islands and propagate northeastward in accord with the Kuroshio frontal unstable wave. However, the sea level anomalies passingIslands are relative weak and Kuroshio variation.through the gaps of Ryukyu have negligible effects on the Kuroshio variation.     

THE SIMULATION OF THE SAR IMAGE OF INTERNAL SOLITARY WAVES IN ALBORAN SEA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＯｃｅａｎｉｎｔｅｒｎａｌｗａｖｅｉｓａｋｉｎｄｏｆｇｒａｖｉｔｙｗａｖｅｇｅｎｅｒａｔｅｄｉｎｔｈｅｓｔｒａｔｉｆｉｅｄｏｃｅａｎ .Ｉｔｐｒｏｄｕｃｅｂｙｔｈｅｉｎｔｅｒａｃｔｉｏｎｏｆｔｉｄｅｃｕｒｒｅｎｔａｎｄｔｏｐｏｇｒａｐｈｙ ,ｓｅａｑｕａｋｅａｎｄｍｏｖｉｎｇｓｈｉｐｗｈｅｎｔｈｅｓｔｒｏｎｇ ,ｓｈａｌｌｏｗｐｙｃｎｏｃｌｉｎｅｉｓ ｐｒｅｓｅｎｔ.Ｔｈｅｉｎｔｅｒｎａｌｗａｖｅｓｉｎｔｈｅｃｏｎｔｉｎｅｎｔａｌｓｈｅｌｆａｒｅａｌｍｏｓｔｔｉｄｅｐｒｏｄ…     

A STUDY OF VELOCITY FIELD IN SHIP WAVES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷｈｅｎａｓｈｉｐｉｓｉｎｍｏｔｉｏｎｏｎｔｈｅｏｃｅａｎ ,ａＶ ｓｈａｐｅｄｓｈｉｐｗａｖｅａｐｐｅａｒｓｂｅｈｉｎｄｔｈｅｓｈｉｐ .ＷｉｔｈＳｙｓ ｔｈｅｔｉｃＡｐｅｒｔｕｒｅＲａｄａｒ (ＳＡＲ ) ,ｔｈｅｓｈｉｐｗａｖｅｃａｎｂｅｄｉｓｃｏｖｅｒｅｄ.ＩｎＲｅｆ.[1]ｉｔｗａｓａｌｒｅａｄｙｒｅｐｏｒｔｅｄｔｈａｔ ,ｗｉｔｈｔｈｅｔｅｃｈｎｏｌｏｇｙｏｆＳＡＲ ,ｔｈｅｙｏｂｔａｉｎｅｄｔｈｅｉｎｆｏｒ ｍａｔｉｏｎａｂｏｕｔｏｆｔｈｅｍｏｔｉｏｎｏｆｓｈｉｐｓｉｎｔｈ…     

EVALUATION OF ADDED RESISTANCE OF KVLCC2 IN SHORT WAVES

The added resistance of KVLCC2 in short and regular head waves has been studied theoretically and experimentally. Model tests are performed to determine how well the asymptotic formula (Faltinsen et al. 1980) predicts the typical level of added resistance in short waves. Because the asymptotic formula neglects the effects of ship motions, it is combined with theoretical methods to calculate the added resistance in long waves using an function to predict the added resistance in the intermediate wavelength region where both ship motions and wave reflection are important. A unique feature of this experiment is that the ship model is divided into three segments to explore the added resistance distribution with respect to hull segment. This paper discusses the sensitivity of experimental results to the quality of the incident regular head waves. Moreover, a novel procedure for analyzing added resistance is described. Finally, the experimentally determined added resistance of KVLCC2 is compared with theoretical results. It is shown that the added resistance from the combined theoretical methods agrees well with experimental results in both the intermediate and short wave regions. The use of hull segments shows that added resistance is concentrated primarily at the bow.     

A PRACTICAL MODEL FOR THE DECAY OF RANDOM WAVES ON MUDDY BEACHES

A practical model has been developed for the propagation and decay of random waves on muddy beaches. In the model, an irregular wave train is characterized by its root-mean-squared wave height, mean wave frequency and mean wave direction. It is also assumed that the wave spectrum is narrow-banded in terms of both frequency and direction. Transformation of root-mean-squared wave height is derived from the conservation of energy flux for individual wave components. Energy dissipation is considered due to both wave breaking and the dynamics response of muddy seabed. The model is applied to waves on the muddy beach at Hangzhou Bay, and the numerical results obtained are shown to be acceptably accurate as comparing with available field data.     

AN ASYMPTOTIC SOLUTION OF VELOCITY FIELD IN SHIP WAVES

1. INTRODUCTION It is well known that behind the ships, V-shaped steady-state ship waves are created while ships move on the water. The classical Kelvin ship wave pattern, which is obtained when a ship is taken as a point impulse moving at a constant velo…     

RADIATION AND DIFFRACTION OF WATER WAVES BY A SUBMERGED CIRCULAR CYLINDER AT FORWARD SPEED

The wave radiation and diffraction by a submerged circular cylinder in deepwater is analysed by the multipole expansion method.The theory is based on the inviscid andlinearized potential flow.     

CHANGES OF MEAN VELOCITY PROFILES IN THE WAVE-CURRENT COMBINED FLOW

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｐｈｅｎｏｍｅｎａｏｆｗａｖｅ ｃｕｒｒｅｎｔｃｏｍｂｉｎｅｄｆｌｏｗａｒｅｖｅｒｙｃｏｍｍｏｎｉｎｅｓｔｕａｒｉｎｅａｎｄｃｏａｓｔａｌｚｏｎｅ .Ｔｈｅｃｏｍｂｉｎｅｄｍｏｔｉｏｎｏｆｗａｖｅａｎｄｃｕｒｒｅｎｔｃｏｎｔｒｏｌｓａｎｄａｆｆｅｃｔｓｍａｎｙｐｈｙｓｉｃａｌｐｒｏｃｅｓｓｅｓｉｎｏｆｆｓｈｏｒｅａｎｄｃｏａｓｔａｌｅｎｇｉｎｅｅｒｉｎｇ ,ｓｕｃｈａｓｓｅｄｉｍｅｎｔｔｒａｎｓｐｏｒｔ,ｐａｒｔｉｃｕｌａｒｌｙｔｈｅｓｕｓｐｅｎｄｅｄｓｅｄｉｍｅｎ…     

WAVES GENERATED BY A 3D MOVING BODY IN A TWO-LAYER FLUID OF FINITE DEPTH

This paper is concerned with the waves generated by a 3-D body advancing beneath the free surface with constant speed in a two-layer fluid of finite depth. By applying Green‘s theorem, a layered integral equation system based on the Rankine source for the perturbed velocity potential generated by the moving body was derived with the potential flow theory. A four node isoparametric element method was used to treat with the solution of the layered integral equation system. The surface and interface waves generated by a moving ball were calculated numerically. The results were compared with the analytical results for a moving source with constant velocity.     

PROPAGATION AND BREAKING OF WAVES ON SLOPING BEACH

In this paper the propagation and breaking of the solitary wave,the sinusoidalwave and the second Stokes wave on a slope of 1/30 are discussed based upon the TUMMACmethod,and the velocity fields of breaking waves on the slope are obtained by using the tracingmethod.The.numerical results for wave deformation are in good agreement with experimentaldata,and the breaker indexes depending on the kinetic criterion agree approximately with previ-ous results.Furthermore,compared with the experimental results measured by Iwagaki and bythe authors,the tendency of velocity distribution of breaking waves computed by this numericalmethod is also satisfactory.     

AN OPTIMIZATION OF EIGENFUNCTION EXPANSION METHOD FOR THE INTERACTION OF WATER WAVES WITH AN ELASTIC PLATE

The hydroelastic interaction of an incident wave with a semi-infinite horizontal elastic plate floating on a homogenous fluid of finite depth is analyzed using the eigenfunction expansion method. The fluid is assumed to be inviscid and incompressible and the wave amplitudes are assumed to be small. A two-dimensional problem is formulated within the framework of linear potential theory. The fluid domain is divided into two regions, namely an open water region and a plate-covered region. In this paper, the orthogonality property of eigenfunctions in the open water region is used to obtain the set of simultaneous equations for the expansion coefficients of the velocity potentials and the edge conditions are included as a part of the equation system. The results indicate that the thickness and the density of plate have almost no influence on the reflection and transmission coefficients. Numerical analysis shows that the method proposed here is effective and has higher convergence than the previous results.     

AN INTEGRAL EQUATION DESCRIBING RIDING WAVES IN SHALLOW WATER OF FINITE DEPTH

1 .　INTRODUCTIONSmall scalewavessuperposedonlarge scalewavesarecalled“ridingwaves” .Small scalewavesonoceansurfacehasaroused greatinterestwiththegreatimprovementofprecisionofmeasuringinstrumentsusedinthefieldofremotesensing .Thisstudyaimsatunderstandingthemotionofthelarge scalewavesandtheenergyexchangebetweenairandseathroughsomeinformationofsmall scalewaves .Henyeyetal .[2 ] derivedthemotione quationtothefirstorderofridingwavesbyusingacanonicalHamiltonianformulationandassumingsmallwave…     

FREE LONG WAVES INDUCED BY WEAKLY NONLINEAR STOKES WAVES PROPAGATING OVER STRONG AMBIENT CURRENT AND AN UNEVEN BOTTOM

1.　ＩＮＴＲＯＤＵＣＴＩＯＮＬｉｕ＆Ｄｉｎｇｅｍａｎｓ[1]　(ｈｅｒｅａｆｔｅｒｒｅｆｅｒｒｅｄｔｏａｓＬ＆Ｄ)ｓｔｕｄｉｅｄｔｈｅｌｏｎｇｗａｖｅｓ,ｆｏｒｃｅｄｌｏｎｇａｎｄｆｒｅｅｌｏｎｇｗａｖｅｓ,ｃａｕｓｅｄｂｙｔｈｅｍｏｄｕｌａｔｅｄＳｔｏｋ?..     

THE GENERATION, EVOLUTION AND PHYSIOLOGICAL RESPONSES OF INTRACELLUAR CALCIUM OSCILLATIONS AND WAVES

The Atri intracellular calcium oscillations model was extended, and two new models were established. Furtherrnore, a unified model of the protein phosphorylation driven by cytosolic calcium oscillations was constructed. The numerical results obtained verified related experimental conclusions. And the analytical expressions of intracellular calcium spiral and target waves in the Xenopus laevis oocyte were obtained, resulting in velocity and waveforrn of calcium solitary pulse wave were found.     

THE STATISTICAL DISTRIBUTION OF EXTREME VALUES OF WAVE-CURRENT FORCES ACTING ON SLENDER CIRCULAR CYLINDER IN IRREGULAR WAVES

Based on model test,the statistical distribution of extreme values of wave-current in-line forces acting on vertical circular cylinder is analyzed in this paper.It is shownthat the results calculated by the simplified method,proposed by authors,agree well with the testdata;Weibull distribution is also adoptable in the region of high KC number, and the shapeparameter a and scale parameter β are related well with KC number respectively.     

NONLINEAR DIFFRACTION OF BICHROMATIC WAVES BY A VERTICAL CYLINDER

We present in this paper a semi-analytical solution for second-order wave diffraction by a vertical circular cylinder in bichromatic waves.On the base of the usual assumption of an irrotational flow,the wave-diffraction problems at second-order sum-fre-quency and difference-frequency are considered.The corresponding second-order diffrac-tion potentials are decomposed into three parts,these are associated with the second-order incident wave,the quadratic forcing terms on the free-surface due to the first-order poten-tial,and the linearised'free-wave'component resulting from the boundary condition on the body surface.A particular solution which exactly satisfies the inhomogeneous free-sur-face condition has been derived.Numerical results for the quadratic transfer functions of the second-order force components are given,and are compared with those obtained using numerical solutions(Kim & Yue,1990,Moubayed & Williams 1995).These quadratic functions are useful in calculating the exciting forces on a circula