大气-水耦合模式下三维太湖湖流场研究

利用太湖区域的大气边界层三维数值模式和三维水动力学数值模式,采用气-水耦合方法,对太湖的风生流特征进行了深入研究。结果表明,太湖区域大气边界层风场具有明显的时空变化特征,与均匀定常风作用下的太湖流场相比,大气-水耦合模式下太湖流场变化较大,形成稳定湖流场所需的时间也较长。三维模式计算出的流速值明显比二维模式大(表层约大一倍,整层平均约大50％),且与实际观测值符合较好。故即使对于像太湖这样的浅水湖泊,三维水动力学模式的应用仍然是很必要的。模拟结果中还发现湖流的上下流矢有时出现非常大的切变,甚至达到了180°。由于浅水湖中仍存在两个边界层(水-气和水-土),故浅水湖中存在流矢的巨大切变是可能的。

NUMERICAL STUDY OF WIND-DRIVEN CURRENT IN TAIHU LAKE WITH THE AIR-WATER COUPLING MODEL

The air-water coupling model including a three-dimensional atmospheric boundary layer and a three-dimensional hydrodynamic model is carried out to simulate the wind-driven current field in Taihu Lake. As compared with the results of the wind driven current under the action of uniform wind field in Taihu Lake, the results computed by the air-water coupling model appear unsteady. The current speed computed by the three-dimensional hydrodynamic model is higher than that computed by the two-dimensional model, and more coincident with the observed data. In addition, the current direction difference between upper and lower levels can be reflected by the three-dimensional model. Finally, it is concluded that the three-dimensional hydrodynamic model is better than the two-dimensional one in describing the wind-driven current in Taihu Lake.