HYDRODYNAMIC MODEL OF THE WEIS-FOGH HYDROFOIL

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KALMAN FILTERING CORRECTION IN REAL-TIME FORECASTING WITH HYDRODYNAMIC MODEL

Accurate and reliable flood forecast is crucial for efficient real-time river management, including flood control, flood warning, reservoir operation and river regulation. In order to improve the estimate of the initial state of the forecasting system and to reduce the errors in the forecast period a data assimilation procedure was often need. The Kalman filter was proven to be an efficient method to adjust real-time flood series and improve the initial conditions before the forecast. A new model integrating the hydraulic model with the Kalman filter for real-time correction of flood forecast was developed and applied in the Three Gorges interzone of the Yangtze River. The method was calibrated and verified against the observed flood stage and discharge during Three Gorges Dam construction periods （2004）. The results demonstrate that the new model incorporates an accurate and fast updating technique can improve the reliability of the flood forecast.     

EMPIRICAL VERIFICATION OF ANISOTROPIC HYDRODYNAMIC TRAFFIC MODEL IN TRAFFIC ANALYSIS AT INTERSECTIONS IN URBAN AREA

In this article,the traffic hydrodynamic model considering the driver’s reaction time was applied to the traffic analysis at the intersections on real roads. In the numerical simulation with the model,the pinch effect of the right-turning vehicles flow was found,which mainly leads to traffic jamming on the straight lane. All of the results in accordance with the empirical data confirm the applicability of this model.     

RESEARCH ON THE CHAOS DYNAMIC MODEL OF RUNOFF

1.　INTRODUCTIONThestudyonrunoffserialhasbeenconductedwithrandommodelsofrunoffserialforalongtime.Inspiteoftheirapplicationsincertaincircumstances,theapplicabilityofrandommodelsislimitedbecausethephysicalmechanismofrunoffprocessisnotcompletelyrandom.Manyresearchershavefoundthatchaosprocessexistsinriverrunoff,rainingandthundering.Chaosisanidentifyingprocesssimilartorandom.Thestateofchaossystemisalwaysconvergedtoacertainnumberofattractorsinphasespace,andthestudyoforderinrandomnessisaveryimpo…     

CALCULATION OF MANOEUVERING HYDRODYNAMIC FORCE INCLUDING THE EFFECT OF VISCOSITY

Based on the method of Chapman and Yamasaki, this paper calculates the wave making hydrodynamic forces acting on a yawed ship. In order to study the effect of viscosity, this paper calculates the wave making resistance of a new ship model whose boundary is formed by adding the displacement thickness on real ship body. The comparisons between the calculated results of a Wigley model and experimental values verify the validity of the new model and the numerical methods.     

THE IMPROVED XINANJIANG MODEL

1.INTRODUCTION Fromthelastcentury,manyhydrological modelshavebeendesignedanddeveloped[1].Many effortshavebeenmadetoschematizethewhole processsoastodevelopmathematicmodel[26].Theserangefromthesimplelumpedcalculationof designdischargetotheconceptualandphysically distributedmodelsrepresentedbythevarious processesbasedontheconservationofmass,ener gyandmomentum[712].Inthephysicallybased hydrologicalmodels,itishighlightedthattheirre spectiveparametersshouldbereflectedinthefield measurements.Suc…     

浅析CSTR水质模型在赣江流域的应用

利用CSTR模型的方法建立了适应于赣江流域复杂河流系统的水质模型，对可以获得的赣江流域水质模型数据进行了分析，同时还对模型进行了验证．结果表明：所建立的水质数学模型能够达到赣江流域预定的规划目标的要求，模似的结果是比较可靠．只是水文数据在空间上比较稀疏，污染源统计数据可信度比较低，但单个水文站点能够比较好地反映流量和其它水文参数的时间变化过程．     

NUMERICAL SIMULATION OF THE HYDRODYNAMIC PERFORMANCE OF AN UNSYMMETRICAL FLAPPING CAUDAL FIN

A comprehensive numerical simulation of the hydrodynamic performance of a caudal fin with unsymmetric flapping motion is carried out. The unsymmetrical motion is induced by adding a pitch bias or a heave bias. A numerical simulation program based on the unsteady panel method is developed to simulate the hydrodynamics of an unsymmetrical flapping caudal fin. A CFD code based on Navier-Stokes equations is used to analyze the flow field. Computational results of both the panel method and the CFD method indicate that the hydrodynamics are greatly affected by the pitch bias and the heave bias. The mean lateral force coefficient is not zero as in contrast with the symmetrical flapping motion. By increasing the pitch bias angle, the mean thrust force coefficient is reduced rapidly. By adding a heave bias, the hydrodynamic coefficients are separated as two parts: in one part, the amplitude is the heave amplitude plus the bias and in the other part, it is the heave amplitude minus the bias. Analysis of the flow field shows that the vortex distribution is not symmetrical, which generates the non-zero mean lateral force coefficient.     

STUDY OF HYDRODYNAMIC FORCES OF SHIPS IN NARROW WATERWAY

1 .　INTRODUCTIONInrestricatedwaterssuchasnarrowwater ways,itisnecessarytoknowthemaneuveringcharacteristicsofships .Thecollisionofshipsisoneofthemajorreasonsofshipwreckintheworld .Thecollisionsmayoccurforavarietyofreasons .Theymaybedue ,amongotherthings ,tohumanerror ,mechanicalfailure ,weatherandwa terconditions .Butthehydrodynamicforcesbe tweentwoshipsandbetweenshipandbank ,theeffectofdepthofwateralsochangethemaneuver ingcharacteristicsofshipsgreatly .Innarrowwa terways ,specially ,the…     

RESEARCH ON THE HYDRODYNAMIC STABILITY OF FIBRE SUSPENSIONS

BRIEFINTRODUCTIONOFTHEPAPER :　Fibresuspensionshavebeenveryfamiliarinnatureandinmanyfieldsofindustry .Researchesofthemin volvemanybranchesofsubjectsandhavegreata cademicvalues .Thisthesisstudiesthestabilityoffibresuspensionswiththeoretical,numericalandexperimentalmethods .Firstthelinearstabilityanalysisisperformedforfibresuspensionsutilizingtheflowstability ,slender bodyandorientationtensortheories .Thegoverningequationsofchanneland pipesuspen sionsofdifferentstabilityhandlingmodesa…     

FINITE ELEMENT NUMERICAL SIMULATION FOR THE HYDRODYNAMIC FIELD EVOLUTION OF GEOTHERMAL WATER IN THE NANWENQUAN ANTICLINE IN CHONGQING IN CHINA

1. INTRODUCTION The Nanwenquan anticline is the drape storing geothermal water. The anticline extends from north to south in Chongqing, the Nanwenquan and Xiaoquan in the middle of the anticline [1]. The two hot springs, and geothermal water in the other …     

EXPERIMENTAL RESEARCH ON CHARACTERISTICS OF HYDRODYNAMIC PRESSURE SPREADING IN THE BASE GAP OF ARCH INVERTED PLUNGE POOL

1 .　INTRODUCTIONForanytypeofplungepoolinhydraulicengi neering ,thehydrodynamic pressurespreadinginthebasegapwhichlocatesbetweenthetieapronandtherockiscloselyrelatedtothestabilizationoftheapron .Pressurecharacteristicsinthebasegapoftheflat bottom plungepoolwereresearchedbymanyauthors ,e .g .,Virgilio[1] atanearlystageandLiu[2 ] ,Zhang[3] andSun[4 ] inrecent years.However ,thebehaviorofthehydrodynamicpres sureinthebase gapofthearchinverted plungepoolisstillunclear .Thesetwotypesareentirel…     

NUMERICAL INVESTIGATION ON THE HYDRODYNAMIC PERFORMANCES OF A NEW SPAR CONCEPT

Recently, the spar platform concept develops quickly in the offshore oil and gas exploitations, especially in deep and ultra-deep water, owing to its benign motion performance, excellent stability and adaptation to wide range of water depth. Many new spar concepts have been put forward with the purpose of reducing fabrication difficulty and cost, while meeting the requirements of exploitation in the meantime. Based on the aims mentioned above, a new spar concept was presented in this article and its hydrodynamics both in operating and survival conditions was studied by means of numerical simulation. Basic model tests were also conducted to calibrate the numerical approach. Following aspects are highlighted: (1) new spar concept, (2) global performance of the spar concept and (3) mooring line analysis.     

NUMERICAL PREDICTION OF SUBMARINE HYDRODYNAMIC COEFFICIENTS USING CFD SIMULATION

The submarine Hydrodynamic coefficients are predicted by numerical simulations.Steady and unsteady Reynolds Averaged Navier-Stokes(RANS) simulations are carried out to numerically simulate the oblique towing experiment and the Planar Motion Mechanism(PMM) experiment performed on the SUBOFF submarine model.The dynamic mesh method is adopted to simulate the maneuvering motions of pure heaving,pure swaying,pure pitching and pure yawing.The hydrodynamic forces and moments acting on the maneuvering submarine are obtained.Consequently,by analyzing these results,the hydrodynamic coefficients of the submarine maneuvering motions can be determined.The computational results are verified by comparison with experimental data,which show that this method can be used to estimate the hydrodynamic derivatives of a fully appended submarine.     

DEVELOPMENT OF TWO-DIMENSIONAL HYDRODYNAMIC AND WATER QUALITY MODEL FOR HUANGPU RIVER

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＨｕａｎｇｐｕＲｉｖｅｒ,ｏｒｉｇｉｎａｔｉｎｇｆｒｏｍｔｈｅＴａｉｈｕ ,ｒｕｎｓａｃｒｏｓｓＳｈａｎｇｈａｉａｎｄｆｅｅｄｓｉｎｔｏＹａｎｇｔｚｅＲｉｖｅｒａｔＷｕｓｏｎｇｋｏｕ .Ｉｔｉｓａｔｉｄａｌｉｎｆｌｕｅｎｃｉｎｇｒｉｖｅｒｗｉｔｈｍｏｒｅｔｈａｎ 5 0ｔｒｉｂｕｔａｒｉｅｓａｍｏｎｇｗｈｉｃｈｓｏｍｅｍａｊｏｒｔｒｉｂｕ ｔａｒｉｅｓａｒｅｓｈｏｗｎｉｎＦｉｇ .1 .Ｆｉｇ .1　ＤｅｐｉｃｔｉｏｎｏｆＨｕａｎｇｐｕＲｉｖｅｒｗａｔｅｒｓｈｅｄＮｏｗａｄａｙｓｔｈ…     

THE HYDRODYNAMIC CHARACTERISTICS OF FREE VARIABLEPITCH VERTICAL AXIS TIDAL TURBINE

The hydrodynamic characteristics of free variable-pitch vertical axis tidal turbine are investigated by combining experime-ntal and numerical simulations.The variations of hydrodynamics are obtained based on testing the kinematics and the dynamics of the turbine under different flow and structural conditions.Through analyzing the movement of the turbine and the characteristics of the flow field by numerical simulations,it is shown how the turbine’s performance is improved.     

水文预报实时反馈校正法

水文预报因受地面因素及降雨时分布不均等常引起较大的误差，利用实时值，配上相应的函数进行修正，以提高预报精度。     

大坝安全监测“动态”数据模型研究

本文介绍了建立“动态”数据模型的思路和一般方法,并将其引入统计回归模型中,提出了两类可应用于大坝安全监测资料分析解释的“动态”模型:“叠合”模型和混合式自回归模型,最后给出了一组应用实例。     

DYNAMIC RESPONSE IN ESTUARIES-AN ANALYTICAL MODEL

A simple analytical model is developed to interview the general features of theestuarine responses induced both by ocean tides and by low-frequency coastal fluctuations andwind forcings.Model estuary is assumed ideally with constant depth and linearly varyingbreadth.The results indicate that the effects of bottom friction coefficient,the water depth andthe breadth variation parameter on the estuarine response field virtually reflect the difference ofthe energy accumulation,transformation and dissipation in estuaries,It is found by comparisonthat there are obvious differences between tidally-induced and low-frequency forcing inducedestuarine variations.For tidal response,bottom friction is a very important factor to affect theresponse magnitude,while for low-frequency response this effect becomes negligible.Thus amore simplified model for low-frequency estuarine response is produced,which gives morestraightforward view to the response characteristics.Moreover,from the model solutions wededuce a general qualification for the estuarine resonance and discuss the relation between theresonance frequency and the estuarine geometry.     

FLUID-STRUCTURE INTERACTION OF HYDRODYNAMIC DAMPER DURING THE RUSH INTO THE WATER CHANNEL

The hydrodynamic damper is a device to decrease the motion of armament carrier by use of the water resistance. When hydrodynamic damper rushes into the water channel with high velocity, it is a complicated flow phenomenon with fluid-structure interaction, free surface and moving interface. Numerical simulation using the Smoothed Particle Hydrodynamics （SPH） method coupled with the Finite Element （FE） method was successfully conducted to predict the dynamic characteristics of hydrodynamic damper. The water resistance, the pressure in the interface and the stress of structure were investigated, and the relationship among the peak of water resistance, initial velocity and actual draught was also discussed. The empirical formula was put forward to predict the water resistance. And it is found that the resistance coefficient is commonly in the range of 0.3 ≤ C ≤ 0.5, when the initial velocity is larger than 50 m/s. It can be seen that the SPH method coupled with the FE method has many obvious advantages over other numerical methods for this complicated flow problem with fluid-structure interaction.