盐度及悬沙联合层化与水流紊动的相互作用研究

Interaction between the stratification due to salinity and suspended sediment and the turbulent flow plays an important role in the hydrodynamic, salinity and sediment transport in estuaries. At present, the salinity stratification and suspended sediment stratification have a lot of research results. However, the interaction mechanism between the stratification due to both suspended sediment and salinity and turbulence is still lack of understanding. Especially the turbulence model for reasonable description of the strong stratification near bed needs further research. The mechanism for the interaction between the stratification due to salinity-suspended sediment and the flow turbulence will be indicated by the oscillation-grid flume experiment and mesoscale numerical simulation. The turbulence model for the salinity and suspended sediment stratification will be proposed to lay a foundation for development of sediment transport model in estuary area. It is of important scientific significance and practical value for better understanding the phenomenon of high suspended sediment concentration near bottom in the Changjiang Estuary and predicting the sediment siltation in the deep-water channel of the Changjiang Estuary.

盐度、悬沙层化与水流紊动的相互作用对于河口地区水动力、盐度和泥沙运动过程具有重要作用，目前虽然对盐度与悬沙层化效应均有不少研究成果，但对盐度和悬沙联合层化与水流紊动相互作用机理尚缺乏深入理解，特别是缺乏合理描述该现象的紊流模型。本项目拟通过振荡格栅水槽实验和细观尺度数值模拟相结合的方法揭示盐度和悬沙联合层化与水流紊动之间的相互作用机理和规律，并在此基础上建立可以描述河口实际尺度条件下盐度和悬沙联合层化的紊流模型，为河口泥沙运动模型的建立奠定基础。上述工作对于理解长江河口近底高含沙运动现象和规律，预测长江口深水航道淤积规律有重要的科学意义和实用价值。

盐度、悬沙层化与水流紊动的相互作用对于河口地区水动力、盐度和泥沙运动过程起着重要作用。本项目采用实验研究、理论分析和数值模拟相结合的方法，对盐度层化、悬沙层化以及盐度和悬沙联合层化与水流紊动之间的相互作用机理和规律进行了研究。项目主要研究内容和取得的成果为：（1）研发了多通道微型电极盐度测量仪和光纤泥沙浓度测量仪，可以进行多点盐度和泥沙浓度的同步实时测量；（2）提出了均匀沙和非均匀沙浓度的无率定测量方法与盐度和悬沙浓度同步测量的修正公式；（3）在振荡格栅水槽中进行了盐度层化、悬沙层化以及盐度与悬沙共同层化下的水体紊动实验，通过试验结果分析，分别提出了水体紊动强度抑制与盐度梯度、悬沙浓度梯度以及盐度和悬沙联合层化的定量关系；（4）通过密度梯度综合考虑盐度层化与悬沙层化影响，建立了包含层化引起垂向紊动抑制的紊流模型，并和三维水动力模型相结合，揭示了理想河口与长江口的层化减阻机理。上述研究成果对于进一步理解长江河口近底高含沙运动现象，预测长江口深水航道淤积规律有重要的科学意义和实用价值。