气候变化领域集成服务门户(CCPortal): Flow Separation and Increased Drag Coefficient in Estuarine Channels With Curvature

CCPortal

DOI	10.1029/2020JC016267
	Flow Separation and Increased Drag Coefficient in Estuarine Channels With Curvature
	Bo T.; Ralston D.K.
发表日期	2020
ISSN	21699275
卷号	125 期号:10
英文摘要	Flow separation has been observed and studied in sinuous laboratory channels and natural meanders, but the effects of flow separation on along-channel drag are not well understood. Motivated by observations of large drag coefficients from a shallow, sinuous estuary, we built idealized numerical models representative of that system. We found that flow separation in tidal channels with curvature can create form drag that increases the total drag to more than twice that from bottom friction alone. In the momentum budget, the pressure gradient is balanced by the combined effects of bottom friction and form drag, which is calculated directly. The effective increase in total drag coefficient depends on two geometric parameters: dimensionless water depth and bend sharpness, quantified as the bend radius of curvature to channel width ratio. We introduce a theoretical boundary layer separation model to explain this parameter dependence and to predict flow separation and the increased drag. The drag coefficient can increase by a factor of 2–7 in “sharp” and “deep” sinuous channels where flow separation is most likely. Flow separation also enhances energy dissipation due to increased velocities in bends, resulting in greater loss of tidal energy and weakened stratification. Flow separation and the associated drag increase are expected to be more common in meanders of tidal channels than rivers where point bars that inhibit flow separation are more commonly found. The increased drag due to flow separation reduces tidal amplitude and affects velocity phasing along the estuary and could result in morphological feedbacks. ©2020. American Geophysical Union. All Rights Reserved.
语种	英语
来源期刊	Journal of Geophysical Research: Oceans
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/186650
作者单位	MIT-WHOI Joint Program, Cambridge, MA, United States; Applied Ocean Physics and Engineering Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
推荐引用方式 GB/T 7714	Bo T.,Ralston D.K.. Flow Separation and Increased Drag Coefficient in Estuarine Channels With Curvature[J],2020,125(10).
APA	Bo T.,&Ralston D.K..(2020).Flow Separation and Increased Drag Coefficient in Estuarine Channels With Curvature.Journal of Geophysical Research: Oceans,125(10).
MLA	Bo T.,et al."Flow Separation and Increased Drag Coefficient in Estuarine Channels With Curvature".Journal of Geophysical Research: Oceans 125.10(2020).