On the turbulent flow structure around an instream structure with realistic geometry
On the turbulent flow structure around an instream structure with realistic geometry
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具有真实几何形状的河内结构周围的湍流结构
DOI：
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发表时间：
2016
期刊：
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通讯作者：
F. Sotiropoulos
中科院分区：
文献类型：
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作者：
Seokkoo Kang;C. Hill;F. Sotiropoulos
我们通过进行实验室水槽实验和利用并行计算进行高分辨率大涡模拟（LES）来研究岩石叶片周围的流动动力学，岩石叶片是一种广泛用于河流恢复的仪器结构。水槽实验在固定床和移动的床条件下进行，分别测量流速和床面高程。通过直接解析构成叶片的岩石的细节和河床上的单个粗糙度元素，对固定床实验进行大涡模拟。LES计算的平均流统计数据与测量结果吻合良好，计算流场分析显示，叶片下游存在两个反向旋转的二次流单元，其源于三维流线在叶片下游侧壁下部的俯冲。为了进一步研究次级流动池在移动的床条件下的作用，将LES结果与在移动的床实验中测量的平衡床高度进行比较。移动的床实验表明，叶片下游存在一个倾斜的砂脊，该砂脊与两个二次流动池碰撞引起的流动会聚线对齐。结果表明，岩石叶片下游的两个反向旋转单元对平均流量和床面切应力以及床面形态动力学具有深远的影响。
We investigate the flow dynamics around a rock vane, a widely used instream structure for stream restoration, by conducting laboratory flume experiments, and carrying out high‐resolution Large Eddy Simulation (LES) taking advantage of parallel computing. The flume experiments are conducted under fixed‐ and mobile‐bed conditions, where the velocities and bed elevations are measured, respectively. The LES is carried out for the fixed‐bed experiment by directly resolving the details of the rocks that constitute the vane and the individual roughness elements on the channel bed. The LES‐computed mean flow statistics show good agreement with the measurements, and the analysis of the computed flow field reveals the existence of two counter‐rotating secondary flow cells downstream of the vane, which originate from the plunging of the three‐dimensional streamlines onto a lower part of the sidewall downstream of the vane. To further examine the role of the secondary flow cells under a mobile‐bed condition, the LES results are compared with the equilibrium bed elevation measured in the mobile bed experiment. The mobile‐bed experiment reveals the existence of an oblique sand ridge downstream of the vane that is aligned with the line of flow convergence caused by the collision of the two secondary flow cells. The results indicate that the two counter‐rotating cells downstream of the rock vane has a profound impact on the mean flow and bed shear stress as well as on the bed morphodynamics.