A General Model for the Helical Structure of Geophysical Flows in Channel Bends
A General Model for the Helical Structure of Geophysical Flows in Channel Bends
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DOI：
10.1002/2017gl075721
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发表时间：
2017-12
影响因子：
5.2
通讯作者：
M. Azpiroz-Zabala;M. Cartigny;E. Sumner;M. Clare;P. Talling;D. Parsons;C. Cooper
中科院分区：
文献类型：
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作者：
M. Azpiroz-Zabala;M. Cartigny;E. Sumner;M. Clare;P. Talling;D. Parsons;C. Cooper
由地球物理流（如河流和海底浊流）形成的曲流河道包含地球上最广泛的沉积物搬运系统。先前对河流的测量表明，曲流弯道处的螺旋流在沉积物搬运和沉积过程中起着关键作用。浊流在密度和流速剖面方面都与河流不同。这些差异以及缺乏对浊流的实地测量，导致了多种关于其弯道处螺旋流的模型。在此，我们展示了对海底浊流中螺旋流的首次测量结果。这10次浊流持续了1 - 10天，厚度达约80米，并呈现出一种一致的螺旋结构。这种结构由两个垂直堆叠的单元组成，底部单元的旋转方向与河流中的螺旋流相反。此外，我们提出了一个通用模型，该模型根据其密度分层预测在河流、河口和浊流中观察到的螺旋流结构的范围。
Meandering channels formed by geophysical flows (e.g., rivers and seafloor turbidity currents) include the most extensive sediment transport systems on Earth. Previous measurements from rivers show how helical flow at meander bends plays a key role in sediment transport and deposition. Turbidity currents differ from rivers in both density and velocity profiles. These differences, and the lack of field measurements from turbidity currents, have led to multiple models for their helical flow around bends. Here we present the first measurements of helical flow in submarine turbidity currents. These 10 flows lasted for 1–10 days, were up to ~80 m thick, and displayed a consistent helical structure. This structure comprised two vertically stacked cells, with the bottom cell rotating in the opposite direction to helical flow in rivers. Furthermore, we propose a general model that predicts the range of helical flow structures observed in rivers, estuaries, and turbidity currents based on their density stratification.