南四湖内风生流及输水期流场的数值模拟研究

Numerical simulation for wind-driven current and water transfer period flow field in Nansi Lake

南四湖属典型的浅水湖泊,湖内地形错综复杂,调水前水流由上级湖流向下级湖,调水后水流通过水泵逐级提升(逆坡)由下级湖流向上级湖,调水前、后水流条件改变了南四湖的流场特征.借助于SMS地表水模拟软件,以南四湖1/10000地形图(CAD版)为基础,考虑湖内各种植物、湖田及航道等对调水的阻隔作用,采用伽辽金有限元法建立了南四湖水流数学模型,进行了不同风况条件下南四湖调水前、后流场的数值模拟研究.结果表明,非调水期南四湖内风生流现象明显;调水期水动力条件发生改变,风对南四湖输水流场的影响较小,可以忽略风应力作用.

The Nansi Lake is typical of shallow Lakes,and the lake terrain is complex.Before water transfer,water flows from superior lake to subordinate lake;while transfered,water flow ascends step by step through water pump from subordinate lake to superior lake（adverse slope）.The flow condition before and after water transfer has changed the characteristics of the flow field of the Nansi Lake.By SMS surface water simulation software,on the basis of the Nansi Lake one over ten thousand topographic map（CAD）,in consideration of the barrier action of plant,shoaly land and river channel on water transfer,the Nansi Lake flow mathematical model was built by Galerkin finite element method and the numerical simulation of the flow field of the Nansi Lake before and after water transfer under different wind condition is done.The research result shows the wind current phenomenon during the period excluding water transfer is quite obvious;and during water transfering period,the hydrodynamic force changes and the influence of wind on the water delivery flow field of the Nansi Lake is minor,so the wind-stress may be ignored.