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dc.contributor.authorBo, Tong  Concept link
dc.contributor.authorRalston, David K.  Concept link
dc.date.accessioned2021-04-09T21:21:48Z
dc.date.available2021-04-14T06:18:32Z
dc.date.issued2020-10-14
dc.identifier.citationBo, T., & Ralston, D. K. (2020). Flow separation and increased drag coefficient in estuarine channels with curvature. Journal of Geophysical Research: Oceans, 125(10), e2020JC016267.en_US
dc.identifier.urihttps://hdl.handle.net/1912/26929
dc.descriptionAuthor Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(10), 2020): e2020JC016267, htps://doi.org/10.1029/2020JC016267.en_US
dc.description.abstractFlow 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.en_US
dc.description.sponsorshipSupport for D. K. R. and the research leading to these results was funded by NSF award OCE‐1634480.en_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.urihttps://doi.org/10.1029/2020JC016267
dc.titleFlow separation and increased drag coefficient in estuarine channels with curvatureen_US
dc.typeArticleen_US
dc.description.embargo2021-04-14en_US
dc.identifier.doi10.1029/2020JC016267


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