2-D NUMERICAL SIMULATION OF RADIONUCLIDE TRANSPORT IN THE LOWER YANGTZE RIVER

The assessment of the radiological impact of the liquid discharges from nuclear power plants is a major issue for the environmental protection. In this study, a numerical model for the radionuclide transport in the aquatic environment is built, based on the hydrodynamic equations, including the complete set of Saint-Venant equations, the sediment transport equations, with consideration of several different particle sizes and the deposition and erosion of the suspended sediments, and the radionuclide transport equations. The exchanges of radionuclides between water, suspended matter and bed sediments are described in terms of kinetic transfer coefficients. The model is used to simulate the transport of the radionuclides discharged from a planned nuclear power plant project to be sited along the lower Yangtze River. From the model results, one may see the detailed temporal-spatial evolution of the radionuclide contamination in the solution, in the suspended matter and in the bed sediments. The model can be used as a basic tool for studying the environmental impacts of the liquid discharges from nuclear facilities on a river system.     

A VERTICAL 2-D NUMERICAL SIMULATION OF SUSPENDED SEDIMENT TRANSPORT

Numerical simulation of sediment transport and bed evolution has become an important technique in the sediment research. In this article,a numerical model of suspended sediment transport was proposed,which was established in the vertical σ coordinate for fitting the free surface and bottom. In the research of the sediment transport,the predominant factors were found to be the eddy diffusion,the settling velocity,the bed condition and so on. By the aid of the model in the article,the contribution of the Rouse parameter to the vertical profile of sediment concentration was clarified,which was identical to the theoretical results. In the comparison of the numerical results with laboratory data,the agreement between experimental data and numerical results was reached except for some data. And the possible reasons for the disagreement were discussed.     

GRID GENERATION AND NUMERICAL SIMULATION OF 2-D RIVER FLOW

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NUMERICAL SIMULATION OF FLOW FOLD OF A RIVER WITH COMPLICATED BOUNDARIES

ＮＵＭＥＲＩＣＡＬ　ＳＩＭＵＬＡＴＩＯＮ　ＯＦ　ＦＬＯＷ　ＦＩＥＬＤ　ＯＦ　Ａ　ＲＩＶＥＲ　ＷＩＴＨ　ＣＯＭＰＬＩＣＡＴＥＤ　ＢＯＵＮＤＡＲＹＳＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＦＬＯＷＦＯＬＤＯＦＡＲＩＶＥＲＷＩＴＨＣＯＭＰＬＩＣＡＴＥＤＢ...     

2-D NUMERICAL SIMULATION OF FLOODING EFFECTS CAUSED BY SOUTH-TO-NORTH WATER TRANSFER PROJECT

Since the General Channel designed for the South-to-North Water Transfer Project in China has to cross many rivers and streams flowing from west to east, there are potentially serious effects additional flooding on the western side of the project alignment. Therefore, a 2-D numerical model for forecasting basin flood disasters was established and verified using historical flood data. The model was applied to researching the interaction between the proposed Project and flooding events for 5 streams in the Anyang River reach as a representative case study. Simulated results indicate that the model could correctly forecast the flood, submerged area and depths, and water surface elevations along the left side of the channel. The discharge capacity and location of hydraulic structures in the transfer canal alignment were analyzed. Then adjustments to the dimensions and positioning of proposed hydraulic structures were recommended at intersections, especially the addition of a channel to transfer flood water from one stream to another, which can effectively limit the sluice and protect the Anyang City from flooding.     

NUMERICAL SIMULATION OF 2-D TIDAL FLOW AND WATER QUALITY UNDER THE CURVILINEAR COORDINATES

This paper presents a numerical method to simulate the 2-D tidal flow and water quality under the curvilinear coordinates. In order to overcome the computational difficulties in natural rivers, such as the complicated boundary figures, the great disparity between length and width of computational domain, etc. , boundary-fitted grid is used, the irregular domain in physical plane is transformed into a rectangular domain in transformed plane, and the depth-averaged momentum equations and mass equation are rewritten and discretized based on the finite volume techniques in curvilinear coordinates. Practical application of the method is illustrated by an example for the Dachangzhen Section of the Yangtze River. A fair agreement between the values measured and computed demonstrates the validity of the method developed.     

HORIZONTAL 2-D BASIC EQUATIONS AND SIMULATION OF INTERCHANGE BETWEEN SUSPENDED SEDIMENT AND BED MATERIALS IN ALLUVIAL RIVER

A set of new 2-D equations of interchange between suspended sediment and bed materials was serived by theoretical deduction based on the systematic summarization and assessment the previous studies of simulating the interchange between suspended sediment and bed materials in the Lower Yellow River. This model was used to simulate the erosion and deposition processes caused by the interchange between suspended sediment and bed materials in a sketch channel. The results show that these equations are well consistent with the laws of interchange between suspended sediment and bed materials. Furthermore, compared with previous models, it has important practical value not only because of strong theoretical foundation, but also for smaller amount of calculating work and convenient application in practice.     

0HORIZONTAL 2-D BASIC EQUATIONS AND SIMULATION OF INTERCHANGE BETWEEN SUSPENDED SEDIMENT AND BED MATERIALS IN ALLUVIAL RIVER

A set of new 2-D equations of interchange between suspended sediment and bed materials was serived by theoretical deduction based on the systematic summarization and assessment the previous studies of simulating the interchange between suspended sediment and bed materials in the Lower Yellow River. This model was used to simulate the erosion and deposition processes caused by the interchange between suspended sediment and bed materials in a sketch channel. The results show that these equations are well consistent with the laws of interchange between suspended sediment and bed materials. Furthermore, compared with previous models, it has important practical value not only because of strong theoretical foundation, but also for smaller amount of calculating work and convenient application in practice.     

3-D NUMERICAL SIMULATION OF SPRAY DIFFUSION ON ENVIRONMENT

An equation of atomization quantity from energy dissipation by hydraulic jump was derived from dimensional analysis. Applying the Gauss diffusion equation, the spray diffusion in valley was studied under the conditions of continuous line source and random wind direction. Considering the spray-rain switching process, coagulation, condensation and evaporation of droplets, the authors calculated the air temperature, air relative humidity, spray density and the rainfall intensity in the lower reaches. The 3-D numerical results agree well with portotype monitoring data.     

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.     

NUMERICAL SIMULATION OF 3-D REAERATION IN BODY-FITTED COORDINATE SYSTEM

1 .　INTRODUCTIONWiththedevelopmentofeconomy ,waterpol lutionbecomesratherserious .ThecontentofDOinwater ,whichisreaerationoccurringattheair watersurfaces ,isanimportantindexofwaterquality .DOcanbalancethewaterecologyandde composetheorganisminwater .ThelackofDOwillthreatenorganisminwater .OncetheDOisdepletedout,organismwilldecomposeinanaero bicconditionandwaterwillturnsmell.Theturbulentdiffusionandtransferofpollu tantinwatermaydilutetheconcentrationofthepollution ,anddecomposedcontamin…     

A 2-D HYDRODYNAMIC MODEL FOR THE RIVER, LAKE AND NETWORK SYSTEM IN THE JINGJIANG REACH ON THE UNSTRUCTURED QUADRANGLES

The main river,the Dongting Lake and river networks in the Jingjiang reach of the Yangtze River constitute a complex water system,for which a full 2-D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems,based on the latest developments of computer technologies and numerical methods.To better handle irregular boundaries and keep the computation cost well in a reasonable limit,unstructured grids of moderate scale are used. In addition,a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods,especially,when the moderate scale gird can not describe flows in narrow river-network channels at low water levels.Theθsemi-implicit method and the Eulerian-Lagrangian Method(ELM)are adopted,which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions.Properties and efficiency of the model are discussed,and it is concluded that the new model is robust and efficient enough for the simulation of a big,complex water system.Validation tests show that the simulation results agree well with field data.It takes about 0.96 h to complete the computation of a 76 d flood,which indicates that the model is efficient enough for engineering applications.     

2-D FLOW AND SEDIMENT SIMULATION FOR THE FLOOD REGULATION OF A RESERVOIR WITH WATER INTAKE

In this paper, the flood regulation by operating the downstream sluice gates for a reservoir with a water intake is studied. The two-dimensional depth-averaged flow equations are solved by the boundary fitted finite volume method (FVM) based on MacCormsck prediction-correction scheme. The bed deformation caused by both the bed load and incoming suspended sediment is determined in a coupled way. The model is used to simulate the practical flood regulation operation of a reservoir. The results have been compared with the physical experiment.     

大涡模拟法的二维形式

本文给出了大涡模拟（ＬＥＳ０法的二维简化形式，选择了标准的后台阶湍流进行考题。计算结果与有关实验十分吻合。为大涡模拟法的工程应用打下了基础。     

NUMERICAL SIMULATION ON 2-D WATER-AIR TWO-PHASE FLOW OVER TOP OUTLET

Flood discharge over top outlet of dam is simu-lated by 2-dimension water-air two-phase mathematical model.Distribution of dynamic pressure, turbulent kinetic energy (k), turbulent dissipation rate (ε) , free water surface and veloci-ty field have been obtained. The simulated results were testedby physical model, which shows that the computed results areidentical with that of the physical model.     

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

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｈｅｄｅｓｉｇｎｏｆｐｌｕｎｇｅｐｏｏｌ,ｔｈｅｆｌｏｗｆｉｅｌｄｓｈｏｕｌｄｂｅｕｎｄｅｒｓｔｏｏｄｉｎｄｅｐｔｈ .Ｉｎｆａｃｔ,ｔｈｅｋｎｏｗｌｅｄｇｅｏｎｔｈｅｆｌｏｗｆｉｅｌｄｉｎｐｌｕｎｇｅｐｏｏｌｉｓｔｈｅｂａ     

3-D NUMERICAL SIMULATION OF TURBULENT FLOW AFFECTED BY THREE GORGE PROJECT UNDER CONSTRUCTION

1. INTRODUCTIONFor the harnessing, exploiting and utilizing of the famous Yangtze River, the Three Gorge Project (TGP) is a key project. It has many profits like flood prevention, power generation, improving navigation condition and offering water resources etc. In 1997, the success in cutoff of the Yangtze River indicates that the first stage of the TGP has been completed. Then the second-stage of TGP began. During the second stage, the cofferdam close to the left bank used for co…     

NUMERICAL SIMULATION OF 3-D TURBULENT FLOW IN THE MULTI- INTAKES SUMP OF THE PUMP STATION

In this article, a numerical model for three-dimensional turbulent flow in the sump of the pump station was presented. A reasonable boundary condition for the flow in the sump with several water intakes at different flow rates was proposed. The finite volume method was employed to solve the governing equations with the body fitted grid generated by the multi-block grid technique. By using the Fluent software, the fluid flow in a model sump of the pump station was calculated. Compared with the experimental result, the numerical result of the example is fairly good.     

THREE-DIMENSIONAL SIMULATION OF MEANDERING RIVER BASED ON 3-D RNG κ-ε TURBULENCE MODEL

A 3-D numerical model for calculating flow in non-curvilinear coordinates was established in this article. The flow was simulated by solving the full Reynolds-averaged Navier-Stokes equations with the RNG κ-ε turbulence model. In the horizontal x-y-plane, a boundary-fitted curvilinear co-ordinate system was adopted, while in the vertical direction, a σ co-ordinate transformation was used to represent the free surface and bed topography. The water level was determined by solving the 2-D Poisson equation derived from 2-D depth averaged momentum equations. The finite-volume method was used to discretize the equations and the SIMPLEC algorithm was applied to acquire the coupling of velocity and pressure. This model was applied to simulate the meandering channels and natural rivers, and the water levels and the velocities for all sections were given. By contrasting and analyzing, the agreement with measurements is generally good. The feasibility studies of simulating flow of the natural fiver have been conducted to demonstrate its applicability to hydraulic engineering research.