The non-linear partial differential (integral) equation often needs to be solved in the computational hydraulics, however, the mathematical theory of its numerical method has yet not been sufficient at present, for example, the development of some theories such as the strict stability analysis, error estimate and convergence proof has been unable to keep pace with the development of the numerical simulation method.

Then, the practical importance of the gas dynamics analogy in computational hydraulics is emphatically expounded. Two flux-vector-splitting (FVS) difference schemes used in CFD are applied to the shallow-water flow computation by this analogy.

Based on the new developments on environment risk appraisal, early-warning system, compute hydraulics and water quality simulation, and so on, several aspects about the system are discussed in this paper, they are as follows:(1) Analyze the characteristics of sudden water pollution accidents in detail, such as uncertainty of space-time, polluted range and suffer objects, arduousness in dealing with those, long time harm on environment, expanding along the basin and unclearness of urgent response subjects;

Among the difficult problems in hydraulics is the flow with a free urface,because, not known a priori,it has to be determined as a part of the solution.

This treatise introduces the application of mathematical model based upon calculation hydraulics, as a tool to solve the problem of determining the treatment level for an urban wastewater plant nearby the river-mouth or estuary area.

Although the hydraulic engineering and hydraulics have gained huge development, many problems have not been recognized and need further study and exploration.

Unsteady shallow water flow over dry beds is at present one of the topics of research in computational hydraulics.

Among the difficult problems in hydraulics is the flow with a free urface,because, not known a priori,it has to be determined as a part of the solution.A finite element method based on the variational principle for variable domains is proposed for this type of problems. As shown in Fig.1, the domain of solution is divided by a prescribed F curve into two sub-domains,the fixed ABEPQGMNOA and the variable EFQPE with the free stream line as its boundary. Triangular elements and linear distribution of ψ are adopted...

Among the difficult problems in hydraulics is the flow with a free urface,because, not known a priori,it has to be determined as a part of the solution.A finite element method based on the variational principle for variable domains is proposed for this type of problems. As shown in Fig.1, the domain of solution is divided by a prescribed F curve into two sub-domains,the fixed ABEPQGMNOA and the variable EFQPE with the free stream line as its boundary. Triangular elements and linear distribution of ψ are adopted for the inner region,while trapezoidal elements and linear distribution of q2 for the variable domain. The unknowns to be solved for are the values of ψ of the nodes and the ordinates of points on the free surface. Equating the partial derivatives of the functional to zero furnishes enough equations,thus,the location of the free surface and the values of ψ are solved for simultaneously. The method is applied to free surface sluice gate flow over spillway and computed pressure distribution agrees satisfactorily with experimental results.

A two-dimensional laterally integrated numerical model has been developed to represent the velocity and salinity distribution along an estuary.The governing equations which express the conservation of mass,momentum and salt or heat content,are solved by a finite diffrence method in combination with spline functions.The influence of the con-vec tive terms on the resulting distributions of velocity and salinity has been evaluated.The model has been applied to the estuary of the Great Whale River and the Little...

A two-dimensional laterally integrated numerical model has been developed to represent the velocity and salinity distribution along an estuary.The governing equations which express the conservation of mass,momentum and salt or heat content,are solved by a finite diffrence method in combination with spline functions.The influence of the con-vec tive terms on the resulting distributions of velocity and salinity has been evaluated.The model has been applied to the estuary of the Great Whale River and the Little Whale River in the James Bay region.Results of the simulation have been presented together with comparison of some observational data.The sensitivity of the model to various values of the stratification parameters that influence vertical diffusion has been studied and some preliminary results presented.The use of the cubic spline formulation in computation hydraulics has been found to be promising and warrants further development.

本文为描述速度和盐度沿河口的分布规律,而发展了二元横向积分的数值模型。表示质量守恒、动量守恒和含盐量或热容量的主管方程,采用样条函数和有限差分方法相结合进行求解。估计了对流项对速度和盐度分布的影响。 本模型已应用于詹姆斯湾(Jams Bay)区域的大鲸河(the Great Whale River)河口和小鲸河(the Little Whale River)河口的环流计算。本中介绍了模拟结果,并与现有实测数据作了比较。研究了计算模型对影响垂直扩散的不同层化参数值的敏感性,提供了一些初步结果。 在计算水力学中采用三次样条公式,证实是有前途的,值得进一步发展。

This treatise introduces the application of mathematical model based upon calculation hydraulics, as a tool to solve the problem of determining the treatment level for an urban wastewater plant nearby the river-mouth or estuary area.Owing to the interaction of runoff and tide, and the changeable deposition and erosion, the complexity of estuary dynamic points up the difficulty to solve the problem by using common calculating method, as the wastewater is discharged into the water course from the community situated...

This treatise introduces the application of mathematical model based upon calculation hydraulics, as a tool to solve the problem of determining the treatment level for an urban wastewater plant nearby the river-mouth or estuary area.Owing to the interaction of runoff and tide, and the changeable deposition and erosion, the complexity of estuary dynamic points up the difficulty to solve the problem by using common calculating method, as the wastewater is discharged into the water course from the community situated at river - mouth.The application of mathematical model offers a more reliable basis for designing Hangzhou wastewater plant.