太湖风生流三维数值模拟试验

本文建立了一个适合太湖的三维水动力学模式，考虑太湖局地风场的影响，模拟了太湖的风生流，模拟结果和二维模式的计算结果相比，流速值较符合实际。另外，研究了太湖地形因子对太湖环流的影响，指出洞庭西山和洞庭东山间狭长的过道区是产生太湖大范围环流的重要原因。为了研究太湖中藻类的治理和富集问题，对不同风向作用下太湖的散度场进行了分析计算，对太湖的梅梁湾和贡湖地区进行分析，结果可归纳为三类：（１）辐合型（对应Ｓ、ＳＷ风）；（２）辐散型（对应Ｎ、ＮＥ风）；（３）并存型（对应Ｗ、ＮＷ、Ｅ、ＳＥ风）。

NUMERICAL SIMULATION OF THREE-DIMENSIONAL WIND-DRIVEN CURRENT IN TAIHU LAKE

A mathematical model of three-dimensional wind-driven current is developed with the consideration of local wind system in Taihu lake. The simulated results on the current circulation are more consistent with the observed data, especially on current speed, in comparison with the simulation with respect to two-dimensional models. In addition, it shows that the topography of the lake basin influences on lake circulation, and the existance of the Xishan Island strongly enhances the current speed in the area between Xishan and Dongshan Islands. The convergence field in Taihu lake induced by different wind directions which influence directly on the distribution of the alga in Taihu lake is computed and analysed. Considering the two bays in the north area of Taihu lake, the convergence field can be divided into three patterns: (1) convergence patterns under S and SW winds: (2) divergence patterns under N and NE winds; and (3) convergence and divergence patterns under W, NW, E and SE winds.In terms of the simulated results. the concentration of blue-green alga in Taihu lake can be known roughly.In conclusion, three-dimensional model is better than two-dimensinal model in simulating wind driven current in large shallow lakes such as Taihu lake. The long corridor between Xishan and Dongshan Islands in Taihu lake is very important to the formation of the lake circulation. The three patterns of convergence fields which result in the different distributions of the concentration of the alga are classified in the paper according to the different wind directions.