鄱阳湖水动力形态结构模式的模拟系统设计与应用

Research and Development of Poyang Lake Hydrodynamic Modeling System Based on Integrated Mode of Moving Boundary

在一般的水动力模拟中,入湖河口的数量和位置基本是不变的。鄱阳湖水位高动态变化的特征,导致了入湖河口数量和位置变化等特殊的运动边界问题。本文在分析水动力模拟的湖泊形态结构特征的基础上,概化了高水位湖相型、中水位涨水型、中水位退水型和低水位河相型4种水动力形态结构模式,以解决高水位变幅导致的边界移动、入湖河口数量和位置变化等运动边界序列问题,4种水动力形态结构模式之间的运动边界问题,采用在计算流体力学领域中现有的干-湿网格法运动边界处理技术,从而形成浅水湖泊复杂边界高动态水位条件下复合模式的运动边界处理方法;并利用MapWinGIS开发控件,实现了不同模式的边界拟合正交曲线格网的生成与模拟结果的可视化;系统采用面向对象的Visual Studio C#和Visual Fortran编程语言,以松散耦合方式将数据前后处理与交互模块与水动力模拟的核心模块进行集成。利用集成的鄱阳湖水动力模拟系统并采用低水位河相型模式对1999年12月6-14日的鄱阳湖水动力进行了模拟,模拟结果表明系统具有较好的运动边界处理效果。

Based on analysis of morphological structure and hydrological characteristics of Poyang Lake,four generalized patterns of the morphological structure and hydrological characteristics were presented for hydrodynamic numerical simulation to solve these problems of moving boundary resulted from two changes of the number and positions of estuaries due to high amplitudes of water level changes of Poyang Lake,which are lacustrine facies pattern in high water level,water-rising pattern in medium water level,water-falling pattern in medium water level,and fluvial facies pattern in low water level.The internal moving boundary problem of each morphological structure and hydrological characteristics pattern was settled by using the existing dry-wet grid method on computational fluid dynamics.Thereby,an integrated method to deal with complicated moving boundary due to high amplitudes of water level changes was presented for shallow lakes.In order to develop Poyang Lake hydrodynamic modeling system,an algorithm based on the open-source component of MapWinGIS for the boundary fitted orthogonal curvilinear grid of each morphological structure and hydrological characteristics pattern was developed for the needs of hydrodynamic simulation and results visualization.Two main modules of Poyang Lake hydrodynamic modeling system,the module of data pro-post processing and data interaction and the module of hydrodynamic numerical simulation were integrated in the form of loose coupling using the programming platforms of Visual C# and Visual Fortran.In order to verify the simulation effect and precision,an experimental simulation for Poyang Lake with gauged data in December 6-14,1999 was carried out using developed Poyang Lake hydrodynamic modeling system.The simulated results show that not only the simulation time is obviously shorted but also the simulated effects,which include lake water boundary,water level,depth and current,are better because of the use of integrated moving boundary method.