NUMERICAL SIMULATION OF TIP-CLEARANCE FLOW IN CASCADE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｐ ｃｌｅａｒａｎｃｅｆｌｏｗｓｏｃｃｕｒｉｎｖａｒｉｏｕｓｅｎｇｉｎｅｅｒ ｉｎｇａｐｐｌｉｃａｔｉｏｎｓｓｕｃｈａｓａｘｉａｌ ｆｌｏｗ ｐｕｍｐｓａｎｄｄｕｃｔ ｅｄｐｒｏｐｅｌｌｅｒｓ .Ｔｈｅｉｎｅｒｔｉａｌｆｏｒｃｅｓａｃｔｉｎｇｕｐｏｎｔｈｅｆｌｕｉｄｉｎｔｈｅｎａｒｒｏｗ ｇａｐｂｅｔｗｅｅｎｂｌａｄｅｔｉｐａｎｄｔｈｅｓｕｒｒｏｕｎｄｉｎｇｗａｌｌａｒｅｓｕｆｆｉｃｉｅｎｔｔｏ ｇｅｎｅｒａｔｅａｔｉｐｌｅａｋａｇｅｖｏｒｔｅｘｏｎｔｈｅｓｕｃｔｉｏｎｓ…     

NUMERICAL SIMULATION OF BED TOPOGRAPHY CHANGES INDUCED BY DEEP WATER NAVIGATION CHANNEL PROJECT IN THE YANGTZE ESTUARY

1 .　INTRODUCTIONWiththedevelopmentofindustriesintheYangtzeestuary ,moreandmoreprojects ,suchasportdevelopments ,waterwayconstruction ,landreclamationaswellascoastalprotectionworks,havebeenconductingintheestuary .Moredetailedknowledgeofthetidehydrodynamicsandsedimenttransportmechanisminthewaterisneededforconstructionandmanagementofthe projectsbe causeofthedifficultiesinmodelingthecharacter isticsoffinecohesivesedimentmovementandthecomplicatedflowsdrivenbyriverdischarge ,tide ,stormsurgeand…     

NUMERICAL SIMULATION OF SOLITARY WAVE RUN-UP AND OVER-TOPPING USING BOUSSINESQ-TYPE MODEL

In this article,the use of a high-order Boussinesq-type model and sets of laboratory experiments in a large scale flume of breaking solitary waves climbing up slopes with two inclinations are presented to study the shoreline behavior of breaking and non-breaking solitary waves on plane slopes.The scale effect on run-up height is briefly discussed.The model simulation capability is well validated against the available laboratory data and present experiments.Then,serial numerical tests are conducted to study the shoreline motion correlated with the effects of beach slope and wave nonlinearity for breaking and non-breaking waves.The empirical formula proposed by Hsiao et al.for predicting the maximum run-up height of a breaking solitary wave on plane slopes with a wide range of slope inclinations is confirmed to be cautious.Furthermore,solitary waves impacting and overtopping an impermeable sloping seawall at various water depths are investigated.Laboratory data of run-up height,shoreline motion,free surface elevation and overtopping discharge are presented.Comparisons of run-up,run-down,shoreline trajectory and wave overtopping discharge are made.A fairly good agreement is seen between numerical results and experimental data.It elucidates that the present depth-integrated model can be used as an efficient tool for predicting a wide spectrum of coastal problems.     

NUMERICAL SIMULATION OF THE TURBULENT FLOW IN ROTATING DUCT

l.INrnODUCT1oNFlowintherotatingductisakindofphenomenonofturbulentflow,whichisoftenfoundintheengineeringapplications,suchasinthecentrifugalcompressor,centrifugalpumpandturbomachinery.Theinvestigationontheductflowisveryimportantfortheen-gineeringpracticejustasthequalityofflowintheductmakesbiginfluenceontheperfor-manceandefficiencyofthemachine.Thestudyontheflowintherotatingductbeganin6os'.JohnsonL1jmeasuredthevelocityofthemainstreaminthetwodimensionalrotatingduct.Comparedwiththeflowinthestati…     

NUMERICAL SIMULATION OF SUMMER CIRCULATION IN THE EAST CHINA SEA AND ITS APPLICATION IN ESTIMATING THE SOURCES OF RED TIDES IN THE YANGTZE RIVER ESTUARY AND ADJACENT SEA AREAS

Based on the COHERENS (a Coupled Hydrodynamical Ecological model for Regional Shelf seas), a three-dimensional baroclinic model for the summer of East China Sea (ECS) was established with the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. The circulation patterns of the Kuroshio Current, the Taiwan Warm Current (TWC), the Tsushima Current and the Yangtze Diluted Water (YDW) were successfully simulated with this model. The calculated results are fairly consistent with previous observations and studies. Based on this baroclinic current field, the Lagranian particles tracking was simulated to estimate the possible origins of the red tides frequently occurring in the Yangtze River estuary and its adjacent sea areas. If there are “seeds” (cysts) of the red tide algae at the seabed of the Taiwan Strait, the offshore of Fujian and Zhejiang Provinces and the northeast Taiwan Island, those are extremely possible sources of the red tides in the Yangtze River estuary and its adjacent sea areas. Field data are needed to confirm it. Numerical simulation to estimate the source of the red tides is a new application of the Lagrangian transport in the marine ecology.     

NUMERICAL SIMULATION OF PARTICLE SEPARATION IN AN OIL-SAND SEPARATOR

ＮＯＴＡＴＩＯＮＳＡ　Ａｒｅａｏｆｉｎｌｅｔ ,ｍ2ａ　Ｃｅｎｔｒｉｆｕｇａｌａｃｃｅｌｅｒａｔｉｏｎ ,ｍ2 /ｓｉ　Ｇｒｉｄｏｆａｘｉａｌｄｉｒｅｃｔｉｏｎｍｌ 　ＭａｘｉｍｕｍｇｒｉｄｎｕｍｂｅｒｏｆｒａｄｉａｌｄｉｒｅｃｔｉｏｎＱ　Ｆｌｕｉｄｍａｓｓｒａｔｅ ,ｍ3/ｓＲｃ 　Ｍａｘｉｍｕｍｒａｄｉｕｓｏｆｃｙｃｌｏｎｅ ,ｍＲｅ　Ｒｅｙｎｏｌｄｓｎｕｍｂｅｒｒ　Ｄｉｍｅｎｓｉｏｎｌｅｓｓｒａｄｉａｌｄｉｓｔａｎｃｅｔ　Ｄｉｍｅｎｓｉｏｎｌｅｓｓｔｉｍｅｕ　Ｄｉｍｅｎｓｉｏｎｌｅｓｓａｘｉａｌｖｅｌｏｃ…     

NUMERICAL SIMULATION OF GROUNDWATER DYNAMICS FOR SONGHUAJIANG RIVER VALLEY IN CHINA

The study area was designed and constructed,based on the simplification of a conceptual model, to develop a three-dimensional groundwater flow model for simulation of two-layers system. Finite difference groundwater flow model was constructed for the Central Songhuajiang River alluvial plain in Northeast China, with the coverage of 786. 6km^2. The grid networks with a spacing of 474. 4m by 509. 5m were used to cover the model area. The trial-and-error technique was used to calibrate the model. The sensitivity of the simulations to the model parameters was studied and the most sensitive parameters that controlling the residual heads distribution in the Songhuajiang River valley were defined.     

NUMERICAL SIMULATION OF TURBULENT SPOTS IN INCLINED OPEN-CHANNEL FLOW

The generation and evolution of turbulent spots in the open-channel flow are simulated numerically by using the Navier-Stokes equations. An effective numerical method with high accuracy and high resolution is developed.The fourth order time splitting methods with high accuracy is proposed. Thre-dimensional coupling difference methods are presented for the spatial discretization of the Poisson equation of pressure and Hemholtz equations of velocity, therefore, the fourth-order thre-dimensional coupling central difference schemes are constituted. The fourth-order explicit upwind-biased compact difference schemes are designed to overcome the difficulty for the general higher-order central differences cheme which is inadaptable in the boundary neighborhood.The iterative algorithm and overall time marching is used to enhance efficiency. The method is applied in the numerical simulation of turbulent spots at various complex boundary conditions and flow domains. The generation and the developing process of turbulent spots are given, and the basic char acteristics of turbulent spots are shown by simulating the evolution of the wall pulse in inclined open-channel flow.     

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

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

废物堆下含水层中流场数值模拟

本文用ＢＥＭ法模拟了废物堆下含水层中的流场，与传统的区域法相比，该法不仅精度高，而且不需进行区域剖分，输入数据和计算工作量少，求解的结果与实测值较吻合。     

STUDY ON THE WIND AND WAVE EXTREME PARAMETERS OF TONKIN GULF IN THE SOUTH CHINA SEA-THE APPLICATIONS OF LAGFD NUMERICAL MODELS

Based on the hindcast of the severest 75 tropical cyclones (hereafter is called TCs) which affected Tonkin Gulf in history, the present paper gives sea surface wind and wave extreme parameters at 38 points corresponding to (1/2)×(1/2)?grid in the Gulf. The research increases our understanding of the meteo-ocean conditions on the whole area and provides basic data for ocean environmental research and engineering design.     

SOME FEATURES OF RING 94S-A KUROSHIO DETACHED EDDY IN THE SOUTH CHINA SEA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎＳｅｐｔｅｍｂｅｒ 1 994,ａｗａｒｍ ｃｏｒｅｒｉｎｇｗａｓｄｉｓ ｃｏｖｅｒｅｄｎｅａｒｔｈｅｃｏｎｔｉｎｅｎｔａｌｓｌｏｐｅｏｆｔｈｅｎｏｒｔｈｅｒｎＳｏｕｔｈＣｈｉｎａＳｅａ (ＳＣＳ ,ｈｅａｒａｆｔｅｒ) ,ａｎｄｗａｓｄｉｓ ｃｕｓｓｅｄｉｎｄｅｔａｉｌｆｏｒｔｈｅｆｉｒｓｔｔｉｍｅ (Ｌｉｅｔａｌ.,1 997;Ｌｉｅｔａｌ.,1 998) .Ｔｈｉｓｒｉｎｇ (Ｒｉｎｇ 94Ｓ ,ｎａｍｅｄａｆｔｅｒｔｈｅｏｂｓｅｒｖｅｄｙｅａｒａｎｄｍｏｎｔｈ)ｉｓａｎｗａｒｍｃｏｒｅａｎｔｉ ｃｙ…     

NUMERICAL SIMULATION OF 3-D CORNER FLOWS IN A CIRCULATING WATER CHANNEL

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｉｒｃｕｌａｔｉｎｇｗａｔｅｒｃｈａｎｎｅｌ (ＣＷＣ)ｈａｓｂｅｅｎｐｌａｙｉｎｇａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｈｙｄｒｏｄｙｎａｍｉｃｅｘｐｅｒｉ ｍｅｎｔｓ,ｓｕｃｈａｓｓｈｉｐｍｏｄｅｌｔｅｓｔｓ,ｏｃｅａｎｅｎｇｉｎｅｅｒｉｎｇ ,ｓｐｏｒｔｓｓｃｉｅｎｃｅｓ,ｅｔｃ .Ｔｏａｃｈｉｅｖｅｈｉｇｈｐｅｒｆｏｒｍａｎｃｅ ,ｉｔｉｓｅｓｓｅｎｔｉａｌｆｏｒａｄｅｓｉｇｎｅｒｔｏｋｎｏｗｔｈｅｄｅｔａｉｌｓｏｆｆｌｏｗｉｎｔｈｅＣＷＣ .Ｂｅｃａｕｓｅｏｆｔｈｅｃ…     

NUMERICAL SIMULATION OF FLOW THROUGH ORIFICE ENERGY-DISSIPATORS IN XIAOLANGDI FLOOD-DISCHAR-GE TUNNEL

1.　INTRODUCTIONThe Xiaolangdi project_ a key water conservancy project on the Yellow River_ isbeing built just now. According to the design scheme. three orifice energy-dissipators willbe installed in each flood-discharge tunnel. It is for the first time that orifice energy-dissipators are used in a large-scale hydraulic engineering.As a kind of internal energy-dissipator,orifices have the following advantages:energy dissipation region is shortand easyto control,and the flow pattern is …     

NUMERICAL SIMULATION OF A MATHEMATICAL MODEL FOR WAVE PROPAGATION ON NON-UNIFORM CURRENT AND DEPTH

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＢｅｒｋｈｏｆｆ( 1 972 )ｄｅｒｉｖｅｄｔｈｅｗｅｌｌ ｋｎｏｗｎｃｏｍ ｂｉｎｅｄｒｅｆｒａｃｔｉｏｎ ｄｉｆｆｒａｃｔｉｏｎｅｑｕａｔｉｏｎｗｈｉｃｈｗａｓａｌｓｏｎａｍｅｄａｓｍｉｌｄ ｓｌｏｐｅｅｑｕａｔｉｏｎ .Ｔｈｅｅｑｕａｔｉｏｎｏｖｅｒ ｃｏｍｅｓｔｈｅｓｈｏｒｔｃｏｍｉｎｇｓｏｆｏｎｌｙｄｉｓｃｕｓｓｉｎｇｒｅｆｒａｃｔｉｏｎｐｈｅｎｏｍｅｎｏｎｆｏｒｔｈｅｒｅｆｒａｃｔｉｏｎｍｏｄｅｌａｎｄｏｎｌｙｓｔｕｄｙ ｉｎｇｄｉｆｆｒａｃｔｉｏｎｐｒｏｂｌｅｍｆｏ…     

NUMERICAL SIMULATION OF 3-D FLOW FIELD IN ARCIFORM PLUNGE POOL

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｈｅｄｅｓｉｇｎｏｆｐｌｕｎｇｅｐｏｏｌ,ｔｈｅｆｌｏｗｆｉｅｌｄｓｈｏｕｌｄｂｅｕｎｄｅｒｓｔｏｏｄｉｎｄｅｐｔｈ .Ｉｎｆａｃｔ,ｔｈｅｋｎｏｗｌｅｄｇｅｏｎｔｈｅｆｌｏｗｆｉｅｌｄｉｎｐｌｕｎｇｅｐｏｏｌｉｓｔｈｅｂａ     

NUMERICAL SIMULATION OF TRANSIENT FLOW AROUND A SHIP IN UNSTEADY BERTHING MOTION

Ship berthing is a specific maneuver operation. The flow around a berthing ship and the forces acting on the hull are quite different from those for a ship in normal navigation. By solving the unsteady Reynolds-Averaged Navier-Stokes (RANS) equations, the transient flow field around a ship undergoing unsteady lateral motion is simulated and the varying lateral hydrodynamic force acting on the hull is evaluated in this article. The numerical results obtained with different turbulence models are analyzed and compared with experimental results and other numerical results published in literature, and a turbulence model more suitable for simulation of the viscous flow around a ship undergoing unsteady berthing is determined.     

NUMERICAL SIMULATION OF GAS-WATER LEAKAGE FLOW IN A TWO LAYERED COALBED SYSTEM

For a two layered coalbed system in possession of the slightly permeable interlayer, a mathematical model was established to describe the methane and water flows between coal seams and the internal migration and the distribution of fluids in a slightly permeable interlayer. Meanwhile, this model has included the potential effect of matrix shrinkage associated with desorption on the coal permeability. The numerical results were obtained by the finite difference method, and then the production forecasts for the two layered coalbed system were conducted in combination with the geological data of a certain area in the Qinshui Basin. Through analyzing the internal migration and distribution of fluids in the slightly permeable interlayer and its effect on the coalbed methane well production, the results indicate that the prediction of the gas production rate and the cumulative gas production will be higher if the permeability of the interlayer is neglected. Furthermore, it is also found that the matrix shrinkage could produce an effect on the coal permeability, thus affecting the production performance.     

NUMERICAL SIMULATION OF NANOPARTICLE COAGULATION IN A POISEUILLE FLOW VIA A MOMENT METHOD

Numerical simulations of coagulating nano-scale aerosols in a two dimensional Poiseuille flow between fixed plates are performed. Evolution of the particle field is obtained by utilizing a moment method to approximate the aerosol general dynamic equation. A moment method is used, which assumes a lognormal function for the particle size distribution and requires knowledge of the first three moments. A Damk？hler number is defined to represent the ratio of the convection time scale to the coagulation time scale. Simulations are performed based on three Reynolds numbers, 100, 500 and 1000, and on three initial particle volume fractions corresponding to Damk？hler numbers 0.1, 0.2 and 1.0. Spatio-temporal evolution of the first three moments along with the geometric mean volume and standard deviation are discussed.