Probabilistic Characterization of Sweep and Ejection Events in Turbulent Flows and Its Implications on Sediment Transport

Wu, Kuan-Ting; Tsai, Christina W.; Wu, Meng‐Jie

doi:10.1029/2021wr030417

Cited by 7 publications

(1 citation statement)

References 80 publications

(162 reference statements)

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“…Numerous models have been developed for coastal sediment transport and morphodynamics, ranging from deterministic coastal area models (Amoudry & Souza, 2011) to more sophisticated stochastic or stochastic-deterministic local scale models (Ancey, 2020;Bohorquez & Ancey, 2015;Tsai et al, 2021;Wu, Tsai, & Wu, 2022). In this study, the widely-used Delft3D model is selected for hydrodynamics, sediment transport and morphology evolution modeling, refer to Lesser et al (2004) for more model details.…”

Section: Model Setupmentioning

confidence: 99%

Modeling the Morphological Responses of the Yellow River Delta to the Water‐Sediment Regulation Scheme: The Role of Impulsive River Floods and Density‐Driven Flows

Wang

Liang

et al. 2023

Water Resources Research

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Morphological evolution of river deltas depends to a large extent on river discharges, which are usually highly unsteady due to natural hydrological cycles and anthropogenic regulations. However, it is unclear that how and to what extent the discharge fluctuations influence the delta morphology. In this study, we focus on the morphological response of the Yellow River Delta to the Water‐Sediment Regulation Schemes, which generate impulsive floods and deliver high sediment load within a short time. Tracking the fate of fluvial sediment released by 10 historical events reveals that 51.3%, 19.7%, and 17.8% of fluvial sediment are deposited in the delta front, the subaerial delta and the prodelta, respectively. Hypopycnal and hyperpycnal flows occur alternately during different phases of the regulation schemes, and the latter contribute to 32% of the deposition volume with 10% of the duration. To explore the effects of river discharge schematizations on delta evolution, numerical experiments are conducted to compare models forced by unsteady and constant discharges, with the latter being a common practice in delta morphology modeling. We show that the constant‐discharge simplification fails to capture the highly‐depositional hyperpycnal flows, leading to dramatic underestimation of river mouth depositions. In addition, we demonstrate that including the 3D flow‐sediment interactions are critical in reproducing the correct plume structures, bed surface sediment compositions and deposition patterns. Our study highlights the importance of proper river discharge schematizations and full consideration of flow‐sediment interactions in modeling deltas affected by episodic river floods and high suspended sediment concentrations.

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Section: Model Setupmentioning

confidence: 99%

Modeling the Morphological Responses of the Yellow River Delta to the Water‐Sediment Regulation Scheme: The Role of Impulsive River Floods and Density‐Driven Flows

Wang

Liang

et al. 2023

Water Resources Research

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Incorporating memory effect into a fractional stochastic diffusion particle tracking model for suspended sediment using Malliavin-Calculus-based fractional Brownian Motion

Shen,

Tsai

2024

Chaos, Solitons & Fractals

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Coherent structures, turbulence intermittency, and anisotropy of gravity currents propagating on a rough and porous bed

et al. 2023

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This study experimentally investigated the impacts of rough and porous (RP) bed and sedimentation processes on the coherent structures, turbulence intermittency, and anisotropy of saline and turbidity currents. Results reveal that the local current concentration responds immediately (saline current) or languidly (turbidity current) to turbulence bursting events. Inside the dense current, the turbulent momentum fluxes in streamwise and vertical directions transfer downstream and downward, which favor the sweep events. Inside the ambient water, the turbulent momentum fluxes in streamwise and vertical directions transfer upstream and upward, contributing to the formation of ejection events. At the current-ambient water interface, the turbulent momentum fluxes in streamwise and vertical directions do not tend to transfer in particular directions resulting in almost equal quantities of sweep and ejection events. The Gram-Charlier series expansion is strictly applicable to probability density functions (PDFs) of the sweep and ejection events but not suitable ideally for PDFs of the outward and inward interaction events. The primary anisotropy invariant map (AIM) of gravity currents starts from the two-component plain strain limit (near the bed). It is followed by the three-dimensional isotropy (inside the dense current and ambient water) and the axisymmetric contraction limit (current-ambient water interface). Finally, it ends in two-dimensional isotropy (near the free surface). This AIM is sensitive to the RP boundary and the sedimentation processes. Along the streamwise direction, the RP boundary causes alternations between the anisotropic and isotropic turbulence, but the arranged pattern of the rough units determines the period of this alternation.

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Probabilistic Characterization of Sweep and Ejection Events in Turbulent Flows and Its Implications on Sediment Transport

Cited by 7 publications

References 80 publications

Modeling the Morphological Responses of the Yellow River Delta to the Water‐Sediment Regulation Scheme: The Role of Impulsive River Floods and Density‐Driven Flows

Modeling the Morphological Responses of the Yellow River Delta to the Water‐Sediment Regulation Scheme: The Role of Impulsive River Floods and Density‐Driven Flows

Incorporating memory effect into a fractional stochastic diffusion particle tracking model for suspended sediment using Malliavin-Calculus-based fractional Brownian Motion

Coherent structures, turbulence intermittency, and anisotropy of gravity currents propagating on a rough and porous bed

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