A 3D unstructured grid nearshore hydrodynamic model based on the vortex force formalism

Zheng, Peng; Li, Ming; A, Dominic A. van der; Zanden, Joep van der; Wolf, Judith; Chen, Xueen; Wang, Caixia

doi:10.1016/j.ocemod.2017.06.003

Cited by 20 publications

(23 citation statements)

References 80 publications

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“…The monotonic decreasing of horizontal Stokes drifts from the surface to bottom layers was highly associated with the hyperbolic function in the expression of the Stokes drift, following a cosh2jk ⇀ jðz þhÞ distribution in the vertical space from both methods. Consequently, the strongest Stokes drift was near the surface layer and the weakest one was close to the bottom, consistent with previous works of Kumar et al (2012) and Zheng et al (2017).…”

Section: Model Comparisons For a Planar Beachsupporting

confidence: 92%

“…7d and e). The presence of the intensified longshore currents detected within the surf zone and near the coast in this study was supported by previous results (Uchiyama et al, 2010;Kumar et al, 2012;Zheng et al, 2017;Ji et al, 2019). This fact suggests that our implementations of both theories are effective and satisfactory in simulating the wave-induced longshore currents in the case of the planar beach.…”

Section: Model Comparisons For a Planar Beachsupporting

confidence: 89%

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Implementation and comparison of the recent three-dimensional radiation stress theory and vortex-force formalism in an unstructured-grid coastal circulation model

Xia

Mao

Niu

2020

Estuarine, Coastal and Shelf Science

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Given the importance of wave-current interaction in estuarine and coastal dynamics, it is crucial to revisit impacts of surface gravity waves on three-dimensional (3D) nearshore circulation. This work investigates waveinduced circulation in three typical coastal systems including an idealized inlet and planar and natural barred beaches, by implementing the recent 3D radiation stress (RS) theory and vortex-force (VF) formalism to an unstructured-grid Finite-Volume Community Ocean Model (FVCOM). In the idealized inlet case, 3D RS generated appreciable currents near barriers and lateral boundaries while VF forced strong flows via breaking and rollerinduced accelerations in front of the inlet. Both simulations indicate vertically varying wave-induced circulation that decreases markedly. In the planar beach with obliquely incident waves, both methods successfully produced surface onshore and bottom undertow, as well as the wave breaking and roller-induced longshore currents. Nevertheless, 3D RS generated unrealistic offshore currents close to the shoreline. The coupled models were validated against observations in the natural barred beach, and results indicate that the 3D RS model agrees slightly better with the observed longshore currents while 3D VF captures the vertical shear of the onshore-offshore flows reasonably. Further investigations suggest that both methods produce the wave breakinginduced surface onshore and bottom undertow successfully, yet they are located further offshore resulting from the 3D RS-induced unrealistic offshore currents. Successful implementations of the paired wave-current theories to the unstructured model would be fundamental and beneficial to the coastal ocean modeling community.

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Section: Model Comparisons For a Planar Beachsupporting

confidence: 92%

Section: Model Comparisons For a Planar Beachsupporting

confidence: 89%

Implementation and comparison of the recent three-dimensional radiation stress theory and vortex-force formalism in an unstructured-grid coastal circulation model

Xia

Mao

Niu

2020

Estuarine, Coastal and Shelf Science

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“…An improved model that eliminates the problem was analytically derived and numerically tested, showing significant improvements in modelled turbulence levels as well as in undertow profiles in the pre-breaking and initial breaking regions (Larsen & Fuhrman, 2018). Zheng et al (2017) revealed that the spatial distributions of TKE across the breaking region can be produced by turbulence closure models, if a cross-shore varying dissipation factor is applied. Though advances in numerical modelling of breaking waves have been made recently, these models can still be improved and the work towards better numerical models will benefit from high-resolution validation measurements of turbulence in various breaking wave conditions.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal distributions of turbulence under bichromatic breaking waves

Zanden

Caceres

et al. 2019

Coastal Engineering

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The present study aims to extend insights of surf zone turbulence dynamics to wave groups. In a large-scale wave flume, bichromatic wave groups were produced with 31.5 s group period, 4.2 s mean wave period, and a 0.58 m maximum wave height near the paddle. This condition resulted in plunging-type wave breaking over a fixed, gravel-bed, barred profile. Optic, acoustic and electromagnetic instruments were used to measure the flow and the spatial and temporal distributions of turbulent kinetic energy (TKE). The measurements showed that turbulence in the shoaling region is primarily bed-generated and decays almost fully within one wave cycle, leading to TKE variations at the short wave frequency. The wave breaking-generated turbulence, in contrast, decays over multiple wave cycles, leading to a gradual increase and decay of TKE during a wave group cycle. In the wave breaking region, TKE dynamics are driven by the production and subsequent downward transport of turbulence under the successive breaking waves in the group. Consequently, the maximum near-bed TKE in the breaking region can lag the highest breaking wave by up to 2.5 wave cycles. The net cross-shore transport of TKE is in the shoaling region primarily driven by shortwave velocities and is shoreward-directed; in the wave breaking region, the TKE transport is seaward-directed by the undertow and the longwave velocities. Downward transport of TKE is driven by the vertical component of the timeaveraged flow. The cross-shore and vertical diffusive transport rates are small relative to the advective transport rates.

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“…In this study, the characteristics and mechanisms of tide-surge interaction in the Pearl River Estuary during Typhoon Hato are studied in detail by using a 3D ocean model (Zheng P. et al, 2017). Along with the use of a blended atmospheric forcing, which merged the Holland parametric model results with the CFSR reanalysis data, the model reproduces the pure astronomical tides and total sea levels reasonably well, especially at Guanchong and Xipaotai, where the distinctive "double-peak" pattern observed in the measured water levels is well-reproduced by the present model.…”

Section: Discussionmentioning

confidence: 99%

“…In this study, a prognostic, three-dimensional coastal-ocean model developed for hydrodynamic-wave coupling (Zheng P. et al, 2017) has been applied to study the tide-surge interaction in the PRE. The model is based on the Finite-Volume Community Ocean Model (FVCOM, by Chen et al, 2003).…”

Section: The Numerical Modelmentioning

confidence: 99%

Tide-Surge Interaction in the Pearl River Estuary: A Case Study of Typhoon Hato

Zheng

Wang

et al. 2020

Front. Mar. Sci.

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In this study, the characteristics and mechanisms of tide-surge interaction in the Pearl River Estuary (PRE) during Typhoon Hato in August 2017 are studied in detail using a 3D nearshore hydrodynamic model. The wind field of Typhoon Hato is firstly reconstructed by merging the Holland parametric tropical cyclone model results with the CFSR reanalysis data, which enables the model to reproduce the pure astronomical tides and storm tides well; in particular, the distinctive oscillation pattern in the measured water levels due to the passage of the typhoon has been captured. Three different types of model runs are conducted in order to separate the water level variations due to the astronomical tide, storm surge, and tide-surge interactions in the Pearl River Estuary. The results show the strong tidal modulation of the surge level, as well as alteration of the phase of surge, which also changes the peak storm tidal level, in addition to the tidal modulation effects. In order to numerically assess the contributions of three non-linear processes in the tide-surge interaction and quantify their relative significance, the widely used "subtraction" approach and a new "addition" approach are tested in this study. The widely used "subtraction" approach is found to be unsuitable for the assessment due to the "rebalance" effect, and thus the new "addition" approach is proposed along with a new indicator to represent the tide-surge interaction, from which more reasonable results are obtained. Detailed analysis using the "addition" approach indicates that the quadratic bottom friction, shallow water effect, and nonlinear advective effect play the first, second, and third most important roles in the tidal-surge interaction in the estuary, respectively.

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A 3D unstructured grid nearshore hydrodynamic model based on the vortex force formalism

Cited by 20 publications

References 80 publications

Implementation and comparison of the recent three-dimensional radiation stress theory and vortex-force formalism in an unstructured-grid coastal circulation model

Implementation and comparison of the recent three-dimensional radiation stress theory and vortex-force formalism in an unstructured-grid coastal circulation model

Spatial and temporal distributions of turbulence under bichromatic breaking waves

Tide-Surge Interaction in the Pearl River Estuary: A Case Study of Typhoon Hato

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