Field observations of turbulence, sediment suspension, and transport under breaking tidal bores

Tu, Junbiao; Fan, Daidu; Voulgaris, G.

doi:10.1016/j.margeo.2021.106498

Cited by 14 publications

(18 citation statements)

References 61 publications

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“…Four different segments of data corresponding to different times in a single 24‐hr tidal cycle are used to examine the effect of the choice of H on the percentage contribution of each quadrant to the total Reynolds stress and are shown in Figure 8. As expected, consistently for all 4 burst segments shown in Figure 8, the contribution of each quadrant decays rapidly as the value of H increases, something in agreement with other studies (Franca et al., 2014; Tu et al., 2021). Ejections and sweeps always maintain a positive contribution to Reynolds stress and are of similar magnitude.…”

Section: Resultssupporting

confidence: 91%

“…The equation above is also used to estimate the contribution of each event type to vertical sediment flux by replacing the quantity < u ′ w ′> with < c ′ w ′> (Soulsby et al., 1994; Tu et al., 2021; Yuan et al., 2009).…”

Section: Methodsmentioning

confidence: 99%

“…It can be seen from the table that the Reynolds stress contribution in French and Clifford (1992) results can reach more than one hundred. We attribute this to the fact that the study area of their study is a typical macrotidal channel with relatively shallow water depth (less than 5 m), these assumptions apply to the results of Tu et al (2021) too.…”

Section: Tidal Characteristic Of Turbulent Coherent Structurementioning

confidence: 99%

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Turbulence Structure and Burst Events Observed in a Tidally Induced Bottom Boundary Layer

Voulgaris

Wang

2022

JGR Oceans

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As a three-dimensional vortex motion with high complexity, disorganization and randomness, turbulence is extremely unstable, unpredictable, and dissipative. With the development of fast responding observation techniques, researchers have carried out extensive research on various aspects of turbulence within the near-bottom boundary layer, including turbulent energy balance (Rippeth et al., 2001;Trowbridge et al., 1999) and intermittence characteristics (Wallace et al., 1972;Willmarth & Lu, 1972). The balance of turbulent kinetic energy (TKE) production and dissipation processes within the bottom boundary layer is controlled by horizontal TKE advection, buoyancy flux, vertical divergence, stratification, and other factors. Experimental verification of this balance has been the subject of numerous investigations (

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Section: Resultssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Tidal Characteristic Of Turbulent Coherent Structurementioning

confidence: 99%

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Turbulence Structure and Burst Events Observed in a Tidally Induced Bottom Boundary Layer

Voulgaris

Wang

2022

JGR Oceans

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“…Following Ruessink (2010), we applied the ogive acceptance range as: −0.3 < Og(f) < 1.3, where estimates outside of this range were eliminated. In addition, referring to Tu et al (2021), we compared the observed ogive curves u′w′ in the empirical form and rejected those that were not well fitted.…”

Section: Wave-turbulence Decomposition and Turbulence Quantitiesmentioning

confidence: 99%

Bottom Drag Variations Under Waves and Currents: A Case Study on a Muddy Deposit off the Shandong Peninsula

Liu

2022

Front. Earth Sci.

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Bottom drag coefficient is one of the key parameters in quantifying shelf hydrodynamics and sediment transport processes. It varies markedly due to dynamic forcing and bed type differences, so a set of empirical values have been used for beds of coarse material where bedforms are often present. In comparison, dramatically fewer such rule-of-thumb values are available for muddy beds. Here, we present results of variations in bottom drag as calculated from in situ measurements by bottom-mounted tripods that were placed across the top of a muddy deposit during two different deployments, one in summer and another in winter. A tidal asymmetry of bottom drag was observed, most likely caused by variations of local bed roughness. For hydrodynamically smooth (Re<2.3×105) flows, computed values of bottom drag coefficient were fairly scattered but still showed an overall decreasing trend with an increase in Reynolds number. The bottom drag coefficient for hydrodynamically rough or transitional flow was typically constant, while the averaged drag coefficient over all observation periods was 1.7×10−3. Smaller waves (bottom orbital velocity ub <0.1 m/s) had a very limited impact on the bottom drag coefficient. However, with an increase in ub, the wave–current interactions can decrease the time-averaged near-bed velocity and enhance turbulent kinetic energy, thus leading to an increase in the drag coefficient.

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“…It is also famous for the largest tidal bore worldwide (Bartsch-Winkler and Lynch, 1988;Chanson, 2012). The estuary has been the subject of a number of studies focusing on the provenance of the estuary (Chen et al, 1990;Zhang et al, 2014Zhang et al, , 2015, hydrodynamics and sediment transport (Pan and Huang, 2010;Xie and Pan, 2013;Fan et al, 2014Fan et al, , 2016Tu et al, 2021), the long-term morphodynamic evolutions as well as the morphological responses to human activities (Dai et al, 2014;Liu et al, 2017;Xie et al, 2017a, Xie et al, 2018, Xie et al, 2021a. Mainly based on the bathymetric and monthly-averaged tidal data in each april, July and November since the 1980s, Xie et al (2021b) recently found that the interannual natural morphological evolution of the estuary plays an important role on the tidal behaviors.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Tidal Dynamics in the Qiantang Estuary: The Importance of Morphological Evolution

Xie

Wang

2021

Front. Earth Sci.

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Despite the increasing number of studies on the river-tide interactions in estuaries, less attention has been paid to the role of seasonal morphological changes on tidal regime. This study analyzes the seasonal interplay of river and tide in the Qiantang Estuary, China, particularly focusing on the influences of the active morphological evolution induced by the seasonal variation of river discharge. The study is based on the high and low water levels at three representative stations along the estuary and daily river discharge through 2015, an intermediate flow year in which a typical river flood occurred, as well as the bathymetric data measured in April, July and November, 2015. The results show strong seasonal variations of the water level in addition to the spring-neap variation. These variations are obviously due to the interaction between river discharge and tide but can only be fully explained by including the effect of morphological changes. Two types of the influences of the variation of the river discharge on the tidal dynamics in the estuary can be distinguished: one is immediately induced by the high flow and the other continues for a much longer period because of the bed erosion and the following bed recovery. Tidal range in the upper reach can be doubled after the flood because of bed erosion and then decrease under normal discharge periods due to sediment accumulation. Over a relatively short term such as a month or a spring-neap tidal cycle, there exist good relationships between the tidal range, tidal amplification in the upper reach and the tidal range at the mouth, and between the hydraulic head over the upper and lower reaches. Such relationships are unclear if all data over the whole year are considered together, mainly because of the active morphological evolution.

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Field observations of turbulence, sediment suspension, and transport under breaking tidal bores

Cited by 14 publications

References 61 publications

Turbulence Structure and Burst Events Observed in a Tidally Induced Bottom Boundary Layer

Turbulence Structure and Burst Events Observed in a Tidally Induced Bottom Boundary Layer

Bottom Drag Variations Under Waves and Currents: A Case Study on a Muddy Deposit off the Shandong Peninsula

Seasonal Tidal Dynamics in the Qiantang Estuary: The Importance of Morphological Evolution

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