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.     

NON-ZONAL BAROCLINIC INSTABILITY IN THE NORTH PACIFIC SUBTROPICAL COUNTERCURRENT

1 .　INTRODUCTIONSincethe 196 0sthesubtropicalcountercurrent(STCC)overthePacifichasbeenfoundtobeaneastwardcurrentexistingintheregion (14 0°E 170°W ,19°N 2 8°N) ,whichcontradictswiththeSver druptransporttheory (YoshidaandKidokoro196 7) ,ithasbecomeanimportanttopicinthephysicaloceanography (Cushman Roison 1984 ;Kubokawa 1997) .AokiandImawaki (1996 )andQiu (1999)foundthatintheSTCCregion ,theed dykineticenergyishigheroverthewesternsidethanovertheeasternside .Qiu (1999)discussedthe…     

THE LONG WAVE OSCILLATIONS IN HARBORS WITH ABSORBING BOUNDARY CONDITIONS

This paper employs finite element method to solve shallow water equations withabsorbing boundary conditions(the third kind,mixed boundary conditions).It is of practicalimportance in the cases that the land boundaries of the coastal area are made of porous mediumallowing sea water flow in or out.The absorbing boundary conditions are treated as naturalboundary conditions in wave equation finite element model.The numerical results for rectangu-lar and quarterly annular harbors indicate that the numerical solutions agree very well with ana-lytic solutions,which are also given in this paper.It is found that the land boundary absorbabili-ty may be significant to long wave oscillations,such as tidal waves in coastal harbors.     

AN EXPERIMENTAL STUDY ON EFFECTS OF THE BETA TOPOGRAPHY ON SURFACE FLOWS IN A ROTATING ANNULUS SUBJECT TO RADIAL TEMPERATURE GRADIENT

1.INTRODUCTIONLaboratory experi ments for rotating and strat-ified flows play ani mportant role in understandingthe large-scale effects in the Earth’s at mosphereand ocean[1-2].It is known that the beta effect,ortheβ-effect,is of great significance for many fowphenomena in geophysical fluid,such as the Leewaves due to large-scale topography and thewestwardintensification in the ocean[3].The longwave inthe at mosphereis generally regarded as theRossby wave,but a disputed opinion[4]was p…     

STUDY OF NONLINEAR LONG WAVE APPOXIMATION IN UNIFORM CHANNELS VIA HAMILTONIAN STRUCTURE

ＳＴＵＤＹＯＦＮＯＮＬＩＮＥＡＲＬＯＮＧＷＡＶＥＡＰＰＯＸＩＭＡＴＩＯＮＩＮＵＮＩＦＯＲＭＣＨＡＮＮＥＬＳＶＩＡＨＡＭＩＬＴＯＮＩＡＮＳＴＲＵＣＴＵＲＥ￥ＸｕＸｉｎ－ｓｈｅｎｇ；ＺｈｏｎｇＷａｎ－ｘｉｅ；ＬｕＹｕ－ｌｉｎ（ＩｎｓｔｉｔｕｔｅｏｆＥｎｇ...     

加箍钢管中的水击波速

本文按圆柱薄壳轴对称弯曲理论计算加箍钢管的变形，得到更为准确的加箍钢管中的水击波速计算公式。     

高应变动测技术中波速确定方法的研究

本文阐述了高应变动测技术中波速确定的主要方法 ,总结分析了它们在高应变动测技术中的缺点 ,并提出了一种利用高应变动测结果来确定桩波速的新方法     

THE APPLICATION OF COKELET''''S WAVE THEORY IN THE CALCULATION OF WAVE-CURRENT FIELD

By using Cokelet's wave theory,the limiting wave height and the relative waveangular frequency in wave-current field were calculated in this paper.It is indicated by numeri-cal calculation that if the water depth is not too small,the result given by authors'calculationare very close to the results of limiting wave height by Dalrymple(1975)and to the data of rel-ative wave angular frequency by linear wave theory;but if water depth is rather small,thereare some discrepancy,     

TIME-DOMAIN ANALYSIS OF WAVE FORCES ON SHIPS WITH FORWARD SPEED

Analyses of wave forces on Wigley and Series 60 ships at forward speedare presented in time domain which is based on a free surface transient Green functionwith linearized condition. The main effort focus on the investigation of the numerical sta-bility of time stepping calculation and the waterline intergal contribution to the excitingforces. Numerical study shows that the stable results can be obtained when a wall-sided as-sumption is used at the stern only and the effect of waterline can be neglected. Compar-isons have been made between the present time domain calculations and other works. Nu-merical results for the added resistance on a C_B=0.8 ship in short waves are presentedbased on the assumption that the steady disturbance of ship hull can be neglected.     

消波墩在正槽式溢洪道急流冲击波中的应用

溢洪道的控制堰下一般接陡坡泄槽,为使陡槽内水流平顺,平面上陡槽以等宽直线布置为佳,但受地形、地质等条件的限制,会采用急流段边墙转折,这就将导致冲击波的产生.消波墩作为陡槽局部抬高的变体,可以有效的克服产生的急流冲击波,有良好的工程应用效果.     

INFLUENCE OF OCEAN INTERNAL WAVE ON PROPAGATION OF UNDERWATER RADIATION NOISE

The underwater acoustic field influenced by a selected ocean internal wave was computed using the Parabolic Equation (PE) method and split-step difference algorithm in this paper. Acoustic field is formed by sound source with different frequency covering the range of radiation noise of ships and submarines. Owing to the adoption of complex variables,sparse matrix, Gaussian source and analysis on the grid size.numerical results are achieved smoothly. The results show that internal wave‘s influence on underwater sound can‘t be neglected, especially for higher sound frequency. So it‘s necessary to take internal wave into account in identifying radiation noise of ships and submarines, namely for sound intensity, transmission loss and spectra shape.     

ON THE FORMATION OF THE BULGE IN A SPILLING BREAKING WATER WAVE

The early stages of a spilling breaking water wave leading to the formation of a bulge on the forward face of the wave are investigated. In this study, simultaneous space-time measurements of the free-surface elevation of a spilling breaking water wave are recorded and analyzed. The analysis, carried out in the frame of reference moving with the crest of the wave,reveals that the formation of the bulge is due to the presence of a shock-like mode. In the previous frame of reference, the shock itself is unsteady but its (spatial) location is time independent and coincides with the "toe" of the bulge. As time increases, the shock undergoes a flip (a reflection symmetry) with respect to the midpoint of our time interval. Such a flip is responsible for an abrupt increase of the wave steepe-ness, which will lead to wave breaking at later times. Following these observations, we present a two-dimensional quantitative model which reproduces both the formation of the bulge and the sudden increase of the wave stee     

THE EFFECTS OF RADIATION STRESS ON WAVE HEIGHTS AND SEA LEVEL IN THE INTERACTION OF COUPLED WAVE-TIDE-SURGE IN THE COASTAL AREA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｎｄｇｅｎｅｒａｔｅｓｂｏｔｈｗａｖｅｓａｎｄｓｔｏｒｍｓｕｒｇｅｓ,ｓｏｔｈｅｉｒ ｇｅｎｅｒａｔｉｏｎｉｓｃｌｏｓｅｌｙｒｅｌａｔｅｄ .Ｆｕｒｔｈｅｒ ｍｏｒｅ ,ｓｔｒｏｎｇｌｙｎｏｎｌｉｎｅａｒｉｎｔｅｒａｃｔｉｏｎｓｂｅｔｗｅｅｎｔｉｄｅｓａｎｄｓｔｏｒｍｓｕｒｇｅｓｅｘｉｓｔｉｎｓｈａｌｌｏｗｗａｔｅｒ .Ｔｈｅｉｎｔｅｒａｃｔｉｏｎｓｂｅｔｗｅｅｎｗａｖｅａｎｄｔｉｄｅ ｓｕｒｇｅｍｏｔｉｏｎ ,ｂｅｔｗｅｅｎｗａｖｅａｎｄｔｈｅｍｅａｎｆｌｏｗｏｒｗａｔｅ…     

DEFORMATION AND BREAKINC OF NONLINEAR WAVE IN WATER OF GRADUALLY VARYING DEPTH

Based upon the perturbation method,this paper used the method of conformalmapping to solve the deformation and breaking of nonlinear waves in water of gradually varyingdepth.The wave characteristics,such as wave deformation,velocity field,breaker type andbreaker height are discussed by the third order approximation.Results obtained are comparedwith experimental data.     

SOLUTION OF A KIND OF LINEAR INTERNAL WAVE EQUATION

1.INTRODUCTIONIn density stratified ocean,vertical displaments can cause internal waves.Take the effectdensity compactness of seawater into account,toscillation frequency isN=(-ρg0ddρz0-Cg22)1/2(whereNis one of the most i mportant environmparameters of ocean dynamics which is callBrunt-Vaisala frequency,gthe gravity acceletion,Cthe traveling speed of sound in seawatBothgandCcan be deemed as constants.Soscholars neglectedg2/C2in expression(1).Itbeen proved that in the seawater200m bel…     

HYDRODYNAMIC ANALYSIS ON WAVE POWER DEVICES IN NEAR-SHORE ZONES

A Boundary Element Method for three-dimensional hydrodynamic analysis ofon-shore wave power devices is presented.The topographic effect near the device is studied.Nu-merical results show that the effect is significant and has to be taken into account.The method isalso available to other similar problems in near-shore zones.     

A NEW MEASURE FOR DIRECT MEASUREMENT OF THE BED SHEAR STRESS OF WAVE BOUNDARY LAYER IN WAVE FLUME

In this article, a shear plate was mounted on the bottom in a wave flume and direct measurements of the smooth and rough bed shear stress under regular and irregular waves were conducted with the horizontal force exerted on the shear plates by the bottom shear stress in the wave boundary layer. Under immobile bed condition, grains of sand were glued uniformly and tightly onto the shear plate, being prevented from motion with the fluid flow and generation of sand ripples. The distribution of the bottom mean shear stress varying with time was measured by examining the interaction between the shear plate and shear transducers. The relation between the force measured by the shear transducers and its voltage is a linear one. Simultaneous measurements of the bottom velocity were carried out by an Acoustic Doppler Velocimeter (ADV), while the whole process was completely controlled by computers, bottom shear stress and velocity were synchronously measured. Based on the experimental results, it can be concluded that (1) the friction coefficient groews considerably with the increase of the Reynolds number, (2) the shear stress is a function varying with time and linearly proportional to the velocity. Compared with theoretical results and previous experimental data, it is shown that the experimental method is feasible and effective, A further study on the bed shear stress under regular or irregular waves can be carried out. And applicability to the laboratory studies on the initiation of sediments and the measurement of the shear stress after sediment imigration.     

AN INVERSE PROBLEM OF WATER WAVE GENERATION IN A WAVE TANK

ＡＮＩＮＶＥＲＳＥＰＲＯＢＬＥＭＯＦＷＡＴＥＲＷＡＶＥＧＥＮＥＲＡＴＩＯＮＩＮＡＷＡＶＥＴＡＮＫＭｉａｏＧｕｏ－ｐｉｎｇ；ＹｏｕＹｕｎ－ｘｉａｎｇ；ＬｉｕＹｉｎｇ－ｚｈｏｎｇ（ＳｈａｎｇｈａｉＪａｏＴｏｎｇＵｎｉｖｅｒｓｉｔｙＳｈａｎｇｈａｉ２０００...     

ANALYSIS OF STATE-CHANGING WATER HAMMER IN A LONG PIPE

Pressure wave propagation along a pipe attached with an active pressure-controlling system at an end was described by an unsteady state-changing motion of the pressure wave fronts, in order to study the interaction among successive waves caused by successive controlling spillovers with the consideration of liquid compressibility due to high head. A model for water hammer propagation was established by using the continuity, momentum, and energy equations. The influence of the wave interactions on the pressure suppression was analyzed. Testing verifications were conducted with a 2575m length and 776m head penstock in hydro-power station. The computed results are in good agrement with the tested ones.     

SONIC SPEED AND SHOCK WAVE IN HIGH VELOCITY AERATED FLOWS FROM HIGH HEAD DISCHARGE STRUCTURES

1 .　INTRODUCTIONWiththedevelopmentofhydropowerstationsinChina ,highdamshavebeenbeingincreasinglybuilt .Alotofhighdamsthatisgreaterthan 10 0minheighthavebeensofarcompleted .Andmanysuperhighdamsover 2 0 0mhighsuchastheErtanandLontanHydropowerStationswerecompletedorareunderconstruction .Someofthemevenhavetheheightsoftheorderof 30 0msuchastheXi aowanandXiluoduoHydropowerStations .Ac cordingtoincompletestatistics ,nearly 30superhighdamsthatisgreaterthan 2 0 0minheighthavebeensofarcomplete…