气候变化领域集成服务门户(CCPortal): Recirculating flow-induced anomalous transport in meandering open-channel flows

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DOI	10.1016/j.advwatres.2020.103603
	Recirculating flow-induced anomalous transport in meandering open-channel flows
	Kim J.S.; Seo I.W.; Baek D.; Kang P.K.
发表日期	2020
ISSN	0309-1708
卷号	141
英文摘要	Channel meanders in rivers induce complex three-dimensional (3D) flow characteristics such as secondary flows and flow recirculation. Helical secondary flows promote transverse dispersion, and flow recirculation zones trap tracers. As a result, these meander-driven flows may cause anomalous transport manifested by unusually elevated levels of tracer concentration at early and late times of breakthrough curves (BTCs). In this study, we perform 3D numerical simulations in meandering channels across a wide range of channel sinuosity to investigate the impact of meander geometry on flow and transport. We solve 3D Reynolds-averaged Navier-Stoke equations blended with a SST k − ω turbulence model to obtain velocity and turbulence fields. We then incorporate the obtained flow fields into a Lagrangian particle tracking model to simulate solute transport. Sinuosity higher than 1.5 leads to the onset of horizontal recirculating flows along the apex outer banks, and these recirculation zones expand as sinuosity increases. The analysis of the transport simulations elucidates that the interplay between the secondary flows and recirculation zones induces anomalous transport. The helical secondary flows bring particles into the recirculation zones by promoting transverse dispersion, and the recirculating flows delay particle transport by the trapping effect. We show that the tail power-law slope and truncated time of BTCs as well as Lagrangian tortuosity distributions change dramatically with the emergence of recirculation zones. These analyses demonstrate that the recirculation zones are acting as the primary driver of anomalous transport. Finally, we successfully predict the observed anomalous transport with a Spatial Markov Model (SMM), which is an upscaled transport model that incorporates Lagrangian velocity distribution and spatial velocity correlation. The successful predictions show that the Lagrangian velocity statistics effectively capture the underlying mechanisms of anomalous transport in meandering open-channel flows. © 2020 Elsevier Ltd
关键词	Dispersions Lagrange multipliers Markov processes Navier Stokes equations Secondary flow Solute transport Tracers Turbulence models Velocity Velocity distribution 3-D numerical simulation Lagrangian particle-tracking model Recirculation zones Reynolds averaged Navier-Stoke equations Three-dimensional (3D) flow Tracer concentration Transport simulation Transverse dispersion Open channel flow meander Navier-Stokes equations open channel flow Reynolds number secondary flow solute transport three-dimensional flow turbulence
语种	英语
来源机构	Advances in Water Resources
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/131787
推荐引用方式 GB/T 7714	Kim J.S.,Seo I.W.,Baek D.,et al. Recirculating flow-induced anomalous transport in meandering open-channel flows[J]. Advances in Water Resources,2020,141.
APA	Kim J.S.,Seo I.W.,Baek D.,&Kang P.K..(2020).Recirculating flow-induced anomalous transport in meandering open-channel flows.,141.
MLA	Kim J.S.,et al."Recirculating flow-induced anomalous transport in meandering open-channel flows".141(2020).