深溪沟与白沙河交汇区水流运动3维数值模拟

河流交汇区干支来流的混掺作用，致使该区域水流结构呈现显著的三维特征。基于都江堰深溪沟与白沙河交汇河段的物理模型资料，利用三维数值模拟技术，探讨了深溪沟与白沙河交汇区的水流结构特性。结果表明：干流汇口处断面的水面线在入汇右侧出现突变，下游附近水面线呈现左岸高于右岸的趋势；支流流量越大，交汇区下游断面的流速就越大，水位就越低；无论支流是否来流，在交汇区入汇下游右岸附近都会形成不同范围的水流分离区，各流量组合条件的分离区顶端形状变化明显，且分离区的几何尺寸参数随水位高程的降低而减小。

3D Numerical Simulation of Flow Characteristics at Confluence Zone Between Shenxigou Stream and Baisha River

The flow structure appears obvious three dimensional property resulted by flow interactions between main river and tributary river. The confluence of Shenxigou stream and Baisha river in Dujiangyan region has the complex terrain, and the confluence reaches have a strong three-dimensional characteristics. Numerical simulation of turbulent water and gas flow was calculated for the flow structure of main stream and tributary stream based on the physical model data. The results were showed that water line appeared mutations on the right side at the position of the confluence. The water surface of the right bank downstream presents higher than the ones of the Left bank Line. The larger tributaries flow, the larger flow velocity at the downstream of confluence zone, the lower the water level. The vicinity of the confluence section did not show significant secondary flow. While the left side of the river bend at downstream formed a secondary flow counterclockwise, accounting two-thirds of cross-section. The secondary flow had obvious impact on sediment motion of the river bed. Whether the tributary is confluent to main stream or not, a diverse range of separation zone would be formed near the right Bank downstream of the confluence. And top shape of the separation zone would change significantly. The size parameters of the separation zone would lower with the water level elevation increase.