波流作用下太湖水体悬浮物输运实验及模拟

利用室内外实验和数学模型对波浪和湖流共同作用下太湖水体悬浮物输运过程进行了研究.结果表明:当太湖日平均风速在2~8m/s时,水体悬浮物再悬浮通量与平均风速符合正相关关系;太湖悬浮物沉降属于絮凝沉降.悬浮物浓度较低时,其沉降速率与浓度无明显的相关关系;而浓度较高时,沉降速率随浓度升高而增大.悬浮物浓度和沉降速率符合Logistic函数;将太湖湖流模型和波浪模型耦合,有效地反映了太湖的水动力过程;在太湖悬浮物模型中,引入底泥起悬条件,将底泥的起悬量与沉降量分开处理,有效地模拟了太湖悬浮物的输运过程.模拟结果表明太湖悬浮物沿岸区域受湖流的影响较大,湖心区域受波浪影响较大.

Experimental and numerical study on the transfer process of suspended matter in the interaction of wave and current in Taihu Lake

Based on the experiment and numerical model,the transfer process of suspended solids(SS) in the interaction of wave and current is studied.The results are as follows:Firstly,when the mean wind speed ranges 2 to 8 meter per second,the relationship between resuspend flux and wind speed shows the positive correlation relation.The formula method of Gansith is suitable for computing the resuspend flux of Taihu Lake.Secondly,when the suspended solids concentration(SSC) is low,no clear relationship is found between the settling velocity and SSC.But settling velocity obviously rises with the increase of SSC while the latter is high.Based on the data from the four hydrostatic experiments,it is found that the settling velocity of suspended matter and the suspended matter concentration fitted in logistic curve.Thirdly,the hydrodynamic process of Taihu Lake is described properly based on coupling the wave and current.Finally,the combined effects of the wave and current are included in the SS model.The amounts of suspended and precipitated sediments near lake bed surface layer are treated separately,the stochastic characteristics of turbulent flow pulsation near lake bed are also considered,and the startup conditions of sediment suspension are introduced to the model.The model elucidates the mutual exchange processes between sediment particles in SS and the active sediments within and on bed surface layer.The simulated results show that the lake current has relatively significant effects on the SSC at littoral areas of Taihu Lake,while SSC at the central area of the lake is mainly influenced by waves.