交汇水流分离区特征研究

交汇水流在天然河流中大量存在,分离区水流特性对泥沙输移和污染物扩散的影响极为显著.当前的研究一般是以流体力学理论为基础,从流线概念定义分离区,且仅分析分离区的二维特性,从工程应用和物理本质的角度,该方法尚不完善.本研究以较为详实的水槽实验资料为基础,提出了基于主流向流速的等值线法定义分离区,并采用流线法和等值线法对实验资料进行比较,发现水流分离区几何尺度随着水深及流量比的变化而变化,而这种变化取决于交汇区域内二次流对流速分布的影响,由此认为等值线法比常用的流线法具有更好的应用意义.

Study on Characteristics of Separation Zone in Confluence River

Confluence River is a common occurrence in natural rivers,and the sediment transportation and pollutant dispersion strongly depend on the characteristics of flow structure in the confluence zone.Prior studies mainly focused on two dimensional properties of the separation zone,in which the variation of separation zone size from water surface to the bottom is often neglected.The experiments were performed in a flume,and the characteristics of separation zone were analyzed by the commonly used streamline and velocity isoline firstly proposed in this study.The velocity isoline method was conducted by the longitudinal velocity contour line for its big impact on flow structure.Based on the analysis of the selected data from prior experiments,the geometry and tendency of the separation zone may be changed with the variation of the different distance to the bottom and the discharge ratio between main and tributary rivers.