洞庭湖地区水系水动力耦合数值模型

A COUPLING HYDRODYNAMIC MODEL ON WATER SYSTEM OF THE DONGTING LAKE AREA

针对洞庭湖地区复杂水系和复杂水情下的实际水流运动特征,建立了完全基于水力学方法的洞庭湖地区水系的一、二维耦合的全局水动力学模型,实现了不同水体数值模拟的自动有机衔接。模型包括湖泊、河网水系两部分。对长江干流荆江段、湘资沅澧四水、三口分流河道,运用能够反映河道主槽和边滩不同行洪特征的扩展一维水量模型进行模拟;对于洞庭湖湖区部分,采用二维非结构的有限体积法建立水动力模型;应用重叠投影法实现模型的耦合。模型具有动边界的自动处理,河道分区计算,分洪、溃堤过程实时模拟等功能。剖分的网格较为细致地刻画了湖区的地形,使模型能够模拟"高水湖相、低水河相"的湖流特征。运用1996年7月的实际洪水过程,进行了模型的验证,较为准确地模拟了实际水流特征。

Hydrodynamics in the Dongting Lake area is very complicated with rivers/lakes interlacement. A coupling 1-D and 2-D unsteady flow model was developed to simulate the flood routing in this area. The model includes two parts： lakes and surrounding rivers. Lake flows were calculated with 2-D unstructured finite volume method, which can fit complex geometry boundary and treat wetting/drying process. 1-D approach was applied in the network with surrounding rivers The Saint-Venant equations used in the approach can calculate floodplain and main channel convergence, which works fine especially in the calculation of natural compound rivers. The model was coupled using overlapping projecting method. To validate the present model, it ran for the flood in July 1996 in the study area. Shown by the results, this model has simulated successfully the characteristics of flows in the lakes and the flood routing in this system.