Emergence of coherent flow structures over a gravel surface: A numerical experiment
Emergence of coherent flow structures over a gravel surface: A numerical experiment
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砾石表面相干流结构的出现：数值实验
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
D. Parsons
中科院分区：
文献类型：
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作者：
R. Hardy;S. Lane;R. Ferguson;D. Parsons
砾石河床河流具有复杂的、多孔的和不规则的表面，其特征在于一系列的形态形式。这些地形结构决定了河床上的流动结构，主要是通过突出碎屑下游尾迹中的旋涡脱落。以前对这些流动结构的研究来自实验研究，这些研究使用了流动可视化或单点测量技术。在这里，我们提出了一个数值实验，其中大涡模拟（LES）是用来研究这些流动结构的产生，演变和破坏的自然水工作的砾石表面。本文中报道的数值模拟表明，有两个不同尺度的边界对浅水流的影响，并强调，在天然河流中的任何一点测得的流量变化将包含本地派生和上游继承的流结构，根据目前的床地形的尺度范围。
Gravel bed rivers have complex, porous, and irregular surfaces, characterized by a range of morphological forms. These topographical structures determine the flow structures that develop over the river bed, primarily by the shedding of vortices in the downstream wake of protruding clasts. Previous research into these flow structures has come from experimental studies, which have used either flow visualization or single‐point measurements techniques. Here we present a numerical experiment where large‐eddy simulation (LES) is used to study the generation, evolution, and destruction of these flow structures over a naturally water worked gravel surface. The numerical simulations reported in this paper show that there are two distinct scales of boundary influence upon the shallow flow and emphasize that the measured flow variability at any one point in a natural river will contain both locally derived and upstream‐inherited flow structures, according to the range of scales of bed topography present.