TYPHOON PROCESS AND ITS IMPACT ON THE SURFACE CIRCULATION IN THE NORTHERN SOUTH CHINA SEA

A severe typhoon Utor,occurring between July 3 and 8,2001,brought heavy rainfall,strong wind and storm surge.Utor was responsible for tremendous destruction and economic losses in Philippines,Taiwan and Guangdong.An air-sea model system (MM5 and Princeton Ocean Model(POM))was built to simulate meteorological dynamics and ocean circulation in the South China Sea(SCS).In the POM the output of MM5 was used as the input data.With an increased number of vertical levels,a high-resolution planetary boundary layer scheme and updated landuse/vegetation data,the accuracy of computing wind,temperature and other meteorological fields are improved in near surface and upper levels in MM5 simulations.The simulated trajectory and wind speed of Utor are close to the observed results.The simulated distribution of rainfall is accorded well with measured data in the Pearl River Delta(PRD)area.At different meteorological stations in Hong Kong,the wind,temperature and sea surface pressure are well simulated.The simulated ocean surface current and surface temperature fields have an obvious rightward-biased response to the typhoon Utor,and the maximum velocity and the lowest temperature region appear in the 30 km of the right side of the typhoon track.The typhoon Utor could make the water 50m under the surface ocean unwell to surface and the ocean surface temperature decrease by about 2°C.     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF TIDES AND CURRENTS IN FUSHAN BAY, QINGDAO

The three-dimensional Princeton Ocean Model (POM) was employed to simulate the tide and current simultanuously for the first time in the Fushan Bay, Qingdao, China By adopting the elevation condition that was combined with the tides M2, $2, K1 and O1 at the open boundary and by choosing the proper value of bottom roughness, the horizontal and vertical distributions of the tidal current and water level variations in the bay were computed. The results agree well with the field observation data, indicating that this model can be used to predict accurately the variation of tides and currents in the Fushan Bay and other costal regions in the future.Our study also provides useful information and a data base for the Olympic Projects that will be conducted in the Fushan Bay in 2008.     

SEASONAL VARIABILITY OF THE INDONESIAN THROUGHFLOW FROM A VARIABLE-GRID GLOBAL OCEAN MODEL

1 .　INTRODUCTIONAsalow latitudepathwayforthewarm ,lowsalinityPacificwatersintotheIndianOcean ,In donesianThroughflow (ITF) playsanintegralpartintheglobalthermohalinecirculationandclimatephenomenon ,andtheheatandfreshwatercarriedbytheITFimpactsthebasinbudgetsofboththePacificandtheIndianOceans (WajsowiczandSchneider 2 0 0 1) .Although ,therecentobserva tionshaverevealedsomespatialandtemporalvari abilityfromintraseasonaltointerannualtimescales ,thereappearstobealargedifferenceinpeaktra…     

NUMERICAL MODELLING OF NATURAL RIVER NETWORK

ＮＵＭＥＲＩＣＡＬＭＯＤＥＬＬＩＮＧＯＦＮＡＴＵＲＡＬＲＩＶＥＲＮＥＴＷＯＲＫ￥ＺｅｎｇＰｉｎｇ；ＬｉＹｕ－ｃｈｅｎｇ（ＤａｌｉａｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙ，Ｄａｌｉａｎ１１６０２３，Ｐ．Ｒ．Ｃｈｉｎａ）ＺｈａｏＷｅｎ－ｑｉａｎ（...     

PRELIMINARY STUDY ON CIRCULATION HEIGHT OF CIRCULATION FLOW WITH THE HORIZONTAL AXIS

1.　INTRODUCTIONCirculationflowisoneofcommonflowpatternsinnaturalrivers.Astherotationaxisishorizontal,andismainlyperpendiculartothemainstream,thiskindofcirculationflowisusuallycalledthehorizontalaxiscirculationflow(Zhang,1996).Itusuallyappearsinlocalareaswherebedboundarieschangesuddenly.Forexample,itexistsincross-riverchanneldugforsunkingpipe,anddownstreamofanapronextension,andsoon.Thehorizontalaxiscirculationareaisalwaystheimportantplacewheresedimentdepositsorerodesandtheerodingordeposi…     

AN ACCURATE SOLUTION OF THE LINEAR THEORY OF THE WIND-DRIVEN OCEAN CIRCULATION-I. THE GENERALIZED SOLUTION

To model the wind-driven ocean circulation of the isobath rectangular basin, the linear vorticity equation with the meridional friction term was used compared to the Munk's theory on the ocean circulation. The generalized solution of the vorticity equation was thus worked out in the sense of Fourier averaging by using the corrected Fourier expansion. The method to obtain the undetermined coefficients was presented using the viscous boundary conditions.     

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.     

A NUMERICAL STUDY ON THE PATH AND ORIGIN OF THE YELLOW SEA WARM CURRENT (YSWC)

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＹｅｌｌｏｗＳｅａ (Ｆｉｇ .1 ) ,ｌｏｃａｔｅｄｉｎｔｈｅｍｉｄｄｌｅｌａｔｉｔｕｄｅ,ｉｓｏｎｅｏｆｔｈｅｍｏｓｔｔｙｐｉｃａｌｓｅｍｉ ｅｎｃｌｏｓｅｄｓｅａｓｉｎｔｈｅｗｏｒｌｄ ,ｗｉｔｈｔｈｅｍａｘｉｍｕｍｄｅｐｔｈｏｆ 80ｍＦｉｇ .1　ＴｏｐｏｇｒａｐｈｙｏｆｔｈｅＹｅｌｌｏｗＳｅａａｎｄｔｈｅＥａｓｔＣｈｉｎａＳｅａｉｎｔｈｅＹｅｌｌｏｗＳｅａｔｒｏｕｇｈ .ＩｔｉｓｃｏｎｎｅｃｔｅｄｗｉｔｈｔｈｅＰａｃｉｆｉｃＯｃｅａｎｔｈｒｏｕｇｈｔｈｅＥＣＳ .Ｔｈｅ…     

A STUDY ON VARIABILITY OF SEA SURFACE TEMPERATURE IN TROPICAL PACIFIC, INDIAN OCEAN AND RELATED AIR CIRCULATION

1 .　INTRODUCTIONOceanscover 71%oftheearth’ssurface ,ab sorb 70 %ofthesolarradiationenergy ,85 %ofwhichisstoredintheoceanicsurfacelayerasaheatsourcedrivingair seamotion ,andsuppy 86%ofthemoistureintheair .Thethermalanddy namicinertiamakestheoceanhavespecial“re membrance”and“low passfilter”roleforatmo sphericvariation .Therefore ,thevariabilityofoceanicthermalsituationandair seainteractionareoneoftheimportantfactorscausingtheshortrangeclimaticchanges[1] .Namias ( 195 9) putfor wardthe…     

NUMERICAL MODELLING OF THE WATER AIR TWO PHASE JET INTO A PLUNGE POOL

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｆｌｏｗｆｉｅｌｄａｎｄｅｎｅｒｇｙｄｉｓｓｉｐａｔｉｏｎｉｎｐｌｕｎｇｅｐｏｏｌａｒｅｏｆｐｒａｃｔｉｃａｌｉｍｐｏｒｔａｎｃｅｆｏｒｄａｍｅｎｇｉｎｅｅｒｉｎｇ．Ｔｈｅａｒｅａｔｉｏｎｈａｓｉｍｐｏｒｔａｎｔｅｆｆｅｃｔｓｏｎｔｈｅｆｌｏｗｉｎｐｌｕｎｇｅｐｏｏｌ［１］　．Ｉｎｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｍａｔｈｅｍａｔｉｃａｌｍｏｄｅｌｓｏｆｗａｔｅｒｆｌｏｗｉｎｈｙｄｒａｕｌｉｃｅｎｇｉｎｅｅｒｉｎｇ，ｔｈｅａｒｅ…     

THREE-DIMENSIONAL NUMERICAL MODELLING OF THE WAVE-IN- DUCED RIP CURRENTS UNDER IRREGULAR BATHYMETRY

A process-based 3-D hydrodynamic model is established to simulate the rip current structures under irregular bathymetry.The depth-varying wave-induced residual momentum,the surface rollers,the turbulent mixing and the wave-current interactions are considered.Experimental datasets are used to validate the model,and it is shown that the model can effectively describe the 3-D structures of the rip currents in both normal and oblique wave incident cases.The flow patterns of the rip currents see various characteristics for different incident wave directions.In the normal incident case,pairs of counter-rotating primary circulation cells are formed,and an offshore rip flow occurs in the embayment troughs.The peak seaward velocities occur at the top of the bed boundary layer,and the undertow is incorporated in addition to the rip currents.In the oblique incident case,the longshore currents are dominant,which result in a meandering flow along the depth contour,and the undertow is weaker compared to that in the normal incident condition.     

NUMERICAL SIMULATION OF THE TIDAL MOTION AND SUSPEND EDSEDIMENT TRANSPORT IN THE RADIAL SANDBANK AREA OF THE SOUTHERN YELLOW SEA

A coupled 2-D numerical model for hydrodynamic-sediment transport was established and applied to simulate the tides, tidal currents and sediment movement in the submarine Radial Sandbank area of the southern Yellow Sea.With a high-resolution topography dataset used in the model,the simulation reproduced a fine-structured current field and erosion-siltation distribution. The modeled results show that,in the area of Radial Sandbanks, reversing tidal current and seabed erosion occurs within troughs while tidal current with more rotary feature and deposition occurs above sandbanks,which indicates the tidal-induced formation of the Radial Sandbanks. During a tidal period, associating with the variation of current speed, erosion alternates with siltation. The seabed deformation depends on the relative strength of erosion and siltation in a tidal period.     

THREE-DIMENSIONAL NUMERICAL MODELLING OF SUBMERGED DIKE ALIGNMENT IN CURVED ESTUARINE CHANNEL

1.INTRODUCTIONSubmerged dikes are frequently built in curveriver and estuarine channels to i mprove navigational conditions and/or to protect banks.Manefforts have been made to study flow characteristics around a dike in a straight channel experi mentally and numerically(Rajaratnamet al.1983;Liet al.1994;Mayerle et al.1995;Tominaga et al1997;Peng et al.1997).However,few studiehave investigated overall flowpatterns around submerged dikes in curved estuarine channels.Although many researc…     

NUMERICAL SIMULATION OF ATOMIZATION RAINFALL AND THE GENERATED FLOW ON A SLOPE

This article studies the atomization rainfall and the generated flow on a slope by numerical simulations.The atomization rainfall is simulated by a unified model for splash droplets and a suspended mist,and the distribution of the diameter of splash rain drops is analyzed.The slope runoff generated by the atomization rainfall is simulated by a depth-averaged 2-D model,and the localization of the rainfall intensity in space is specially considered.The simulation results show that:(1) the median rain size of the atomization rainfall increases in the longitudinal direction at first,then monotonously decreases,and the maximum value is taken at the longitudinal position not in consistent with the position where the maximum rain intensity is taken.In the lateral direction the median rain size monotonously decreases,(2) since the atomization rainfall is distributed in a strongly localized area,it takes a longer time for its runoff yield to reach a steady state than that in the natural rainfall,the variation ranges of the water depth and the velocity in the longitudinal and lateral directions are larger than those in the natural rainfall.     

A NUMERICAL MODEL OF FLOW FIELD AND WATER QUALITY FOR TIDAL REGIONS BASED ON TRIANGULAR MESHES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＵｐｔｏｎｏｗ ,ｔｈｅｒｅｐｏｒｔｓｆｏｒｓｏｌｖｉｎｇ 2Ｄｄｅｐｔｈ ｉｎｔｅｇｒａｔｅｄｅｑｕａｔｉｏｎｓｏｆｆｌｏｗａｎｄｍａｓｓｔｒａｎｓｐｏｒｔｉｎｔｉｄａｌｒｅｇｉｏｎｈａｖｅｂｅｅｎｉｎｔｒｏｄｕｃｅｄｉｎｌａｒｇｅｎｕｍ ｂｅｒｓ .ＦｒｏｍｔｈｅｂｅｇｉｎｎｉｎｇｏｆＹａｎｅｎｋｏ[1] .ＴｈｅＦｉ ｎｉｔｅＤｉｆｆｅｒｅｎｃｅＭｅｔｈｏｄ (ＦＤＭ )ｈａｓｂｅｅｎｗｉｄｅｌｙａｐｐｌｉｅｄｂｙＦａｌｃｏｎｅｒ[2 ] ,ＶｉｎｃｅｎｚＣａｓｕｌｌｉ[3,5] ,ＨｅＳｈ…     

NUMERICAL STUDY ON THE PURIFICATION PERFORMANCE OF RIVERBANK

During the rain time, the runoff infiltrates into the riverbank through the collecting gutter and slope surface. The city runoff is generally polluted by organic, oil, heavy metal particulates, etc. The pollutants moving with the water through the riverbank experience advection, dispersion, diffusion, adsorption, biochemical reaction and plant uptaking processes. In this article, a mathematical model was developed to simulate the performance of pollutant removal of the riverbank. The model took those main mechanisms into account. The modified Richards equation was used in simulating flow field. The mass balance law was employed in deriving the equation for pollutant transport, where the diffusion and dispersion were described with the Fick-type law, the adsorption was macroscopically expressed as form isotherm, and the bio-chemical degradation process was assumed to follow the Monod kinetics. The NH3-N and TP were considered in the present model. The mathematical model was descritized with a finite element numerical model, which was applied to two types of model riverbanks. In the model test, the hydraulic loading was assumed to have the intermittent pattern simulating the storm runoff of certain return period, and the values of the rainfall runoff and concentrations of the NH3-N and TP were taken from the model test. The computed overall removal rates for the NH3-N and TP in 6 cases are in the range of 88%-98%, 87%-97%, respectively. The differences between the computed and tested overall removal rates for the NH3-N and TP are less than 5%. The time-varying oscillation pattern of the concentrations of the NH3-N and TP were rationally simulated, which shows that the model presented in this article can be used to assess the purification performance of the riverbank constructed with sand or soil.     

NUMERICAL PREDICTION OF PROPELLER EXCITED ACOUSTIC RESPONSE OF SUBMARINE STRUCTURE BASED ON CFD,FEM AND BEM

A mesh-less Refined Integral Algorithm (RIA) of Boundary Element Method (BEM) is proposed to accurately solve the Helmholtz Integral Equation (HIE).The convergence behavior and the practicability of the method are validated.Computational Fluid Dynamics (CFD),Finite Element Method (FEM) and RIA are used to predict the propeller excited underwater noise of the submarine hull structure.Firstly the propeller and submarine’s flows are independently validated,then the self propulsion of the "submarine+propeller" system is simulated via CFD and the balanced point of the system is determined as well as the self propulsion factors.Secondly,the transient response of the "submarine+ propeller" system is analyzed at the balanced point,and the propeller thrust and torque excitations are calculated.Thirdly the thrust and the torque excitations of the propeller are loaded on the submarine,respectively,to calculate the acoustic response,and the sound power and the main peak frequencies are obtained.Results show that:(1) the thrust mainly excites the submarine axial mode and the high frequency area appears at the two conical-type ends,while the torque mainly excites the circumferential mode and the high frequency area appears at the broadside of the cylindrical section,but with rather smaller sound power and radiation efficiency than the former,(2) the main sound source appears at BPF and 2BPF and comes from the harmonic propeller excitations.So,the main attention should be paid on the thrust excitation control for the sound reduction of the propeller excited submarine structure.     

基于扬压力实测资料的古田溪四级大坝稳定分析

针对古田溪四级大坝部分坝段坝基扬压力较大的问题，应用坝基总扬压力模型和概率法对坝基扬压力性态和可能极值进行了分析，由此进一步分析了典型坝段的稳定状况。     

SEASONAL VARIATIONS OF CIRCULATION AND SUSPENDED MATTER TRANSPORT IN THE YELLOW AND EAST CHINA SEAS

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＹｅｌｌｏｗＳｅａａｎｄＥａｓｔＣｈｉｎａＳｅａ (ＥＣＳ)ａｒｅｍａｒｇｉｎａｌｓｅａｓｏｆｔｈｅｎｏｒｔｈｗｅｓｔＰａｃｉｆｉｃＯｃｅａｎａｎｄｈａｖｅｅｘｐａｎｓｉｖｅｃｏｎｔｉｎｅｎｔａｌｓｈｅｌｖｅｓ .ＴｈｅｕｎｉｑｕｅａｎｄｓｔｒｉｋｉｎｇｆｅａｔｕｒｅｓｏｆｔｈｅＹｅｌｌｏｗＳｅａａｎｄｔｈｅＥＣＳａｒｅｔｈａｔｔｈｅｒｅａｒｅｓｔｒｏｎｇｔｉｄａｌｃｕｒｒｅｎｔ ,ｓｔｒｏｎｇｍｏｎｓｏｏｎｉｎｆｌｕｅｎｃｅａｎｄｆｒｅｓｈｗａｔｅｒｉｎｆｌｏｗｆｒ…     

NUMERICAL SIMULATION OF HYDRODYNAMIC CHARACTERISTICS ON AN ARC CROWN WALL USING VOLUME OF FLUID METHOD BASED ON BFC

In the present study, a new algorithm based on the Volume Of Fluid (VOF) method is developed to simulate the hydrodynamic characteristics on an arc crown wall. Structured grids are generated by the coordinate transform method in an arbitrary complex region. The Navier-Stokes equations for two-dimensional incompressible viscous flows are discretized in the Body Fitted Coordinate (BFC) system. The transformed SIMPLE algorithm is proposed to modify the pressure-velocity field and a transformed VOF method is used to trace the free surface. Hydrodynamic characteristics on an arc crown wall are obtained by the improved numerical model based on the BFC system (BFC model). The velocity field, the pressure field and the time profiles of the water surface near the arc crown wall obtained by using the BFC model and the Cartesian model are compared. The BFC model is verified by experimental results.