Estuarine residual flow induced by eddy viscosity-shear covariance: Dependence on axial bottom slope, tidal intensity and constituents

Chen, W.; Swart, H.E. de

doi:10.1016/j.csr.2018.07.011

Cited by 7 publications

(2 citation statements)

References 35 publications

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“…Nonetheless, spatial and temporal variability of the eddy viscosity can give rise to more complex dynamics (see, e.g., Geyer and MacCready 2014). Of particular relevance here is the generation of a more complex vertical flow structure in strongly stratified situations due to eddy viscosity-shear covariance circulation (ESCO circulation) (Cheng et al 2013;Chen and de Swart 2018;Dijkstra et al 2017). However, this dynamics should emerge naturally when an appropriate one-dimensional model for the horizontal density gradient is used to force the flow.…”

Section: Discussionmentioning

confidence: 99%

Analysis of one-dimensional models for exchange flows under strong stratification

et al. 2019

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One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with these models is that the horizontal density gradient is usually imposed as a constant, leading to non-physically high stratification known as runaway stratification. Here, we propose two new parametrizations of the horizontal density gradient leading to one-dimensional models able to tackle strongly stratified exchange flows at high and low Schmidt number values. The models are extensively tested against results from laminar two-dimensional simulations and are shown to outperform the models using the classical constant parametrization for the horizontal density gradients. Four different flow regimes are found by exploring the parameter space defined by the gravitational Reynolds number Re g , the Schmidt number Sc, and the aspect ratio of the channel. For small values of Re g , when diffusion dominates, all models perform well. However, as Re g increases, two clearly distinct regimes emerge depending on the Sc value, with an equally clear distinction of the performance of the one-dimensional models.

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Section: Discussionmentioning

confidence: 99%

Analysis of one-dimensional models for exchange flows under strong stratification

et al. 2019

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“…Earlier studies have demonstrated the importance of the alongchannel dynamics in the interactions between tidally varying turbulent mixing (quantified by the vertical eddy viscosity) and tidally varying velocity shear (Jay and Musiak, 1994;Stacey et al, 2008;Burchard et al, 2011;Cheng et al, 2011;Cheng et al, 2013;Dijkstra et al, 2017;Chen and de Swart, 2018;Cheng et al, 2020). In a predominantly well-mixed system, the eddy viscosity-shear covariance (ESCO) mechanism contributes to exchange flows with a structure similar to that of the flow driven by the density gradient, but this mechanism appears to be more important than other contributing factors.…”

Section: Introductionmentioning

confidence: 99%

Subtidal secondary circulation induced by eddy viscosity-velocity shear covariance in a predominantly well-mixed tidal inlet

et al. 2023

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The secondary circulation in a predominantly well-mixed estuarine tidal inlet is examined with three-dimensional numerical simulations of the currents and density field in the German Bight. Simulations analyze two complete neap and spring tidal cycles, inspired by cross-section measurements in the tidal inlet, with a focus on subtidal time scales. The study scrutinizes the lateral momentum balance and quantifies the individual forces that drive the residual flow on the cross-section. Forces (per unit mass) from the covariance between eddy viscosity and tidal vertical shear (ESCO) play a role in the lateral momentum budget. During neap tide, the ESCO-driven flow is weak. Accelerations driven by advection dominate the subtidal secondary circulation, which shows an anti-clockwise rotation. During spring tide, the ESCO acceleration, together with the baroclinicity and centrifugal acceleration, drives a clockwise circulation (looking seaward). This structure counteracts the advection-induced flow, leading to the reversal of the secondary circulation. The decomposition of the lateral ESCO term contributors reveals that the difference in ESCO between neap and spring tides is attributed to the change in the vertical structure of lateral tidal currents, which are maximum near the bottom in spring tide. The findings highlight the role of the tidally varying vertical shears in the ESCO mechanism.

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Influence of asymmetric tidal mixing on sediment dynamics in a partially mixed estuary

Yang,

Liang,

Ren

et al. 2023

Acta Oceanol. Sin.

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Estuarine residual flow induced by eddy viscosity-shear covariance: Dependence on axial bottom slope, tidal intensity and constituents

Cited by 7 publications

References 35 publications

Analysis of one-dimensional models for exchange flows under strong stratification

Analysis of one-dimensional models for exchange flows under strong stratification

Subtidal secondary circulation induced by eddy viscosity-velocity shear covariance in a predominantly well-mixed tidal inlet

Influence of asymmetric tidal mixing on sediment dynamics in a partially mixed estuary

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