On the Dependency of Bottom Drag and the Eddy Viscosity upon Flow Structure in the Coastal Boundary Layer

Zhong，Yao Zhao1,2,3; Chien，Hwa2; Lin，Meng Yu4; Wargula，Anna5; Chen，Jia Lin6

2022-03-01

10.3390/jmse10030324

Journal of Marine Science and Engineering   影响因子和分区

2077-1312

The physical processes governing coastal exchange between the surf zone, the inner shelf, and the open ocean is critical for estimating mass exchange and its impact on ecological processes. The present study combined field measurements and theoretical approaches to explore the hydrodynamics in the coastal boundary layer (CBL) in which both bottom drag and shore friction affect the transport and mixing processes. Observed drifter-cluster trajectories in a nearly alongshore-uniform coastal area showed that the occurrence of current reversal varies with cross-shore distance, which confirmed the tidal phase difference between different cross-shore distances predicted by the proposed CBL model. According to the CBL model, tidal phase difference is affected by the bottom drag coefficient and horizontal eddy viscosity coefficient. With the results of three experiments under different wave conditions, this study also discusses the effects of waves on the CBL. Data analysis based on observations indicates that the bottom drag term is closely related to the bottom shear stress induced by the interactions of waves and currents. The bottom drag coefficient under the more energetic wave condition was much greater than that under milder wave conditions during the experiment. The study also suggests that in addition to pressure gradient and bottom drag, flow structure is subject to lateral stress, which reflects the impact of shoreline roughness in the nearshore region and that the estimated eddy viscosity coefficient decreases linearly with distance from the shoreline.

Bottom drag Coastal boundary layer Eddy viscosity Wave-current interaction

SCI

英语

其他

National Natural Science Foundation of China[41876004];Ministry of Science and Technology, Taiwan[MOST 107-2611-M-006-004-];Ministry of Science and Technology, Taiwan[MOST 109-2621-M-008-005-];

Engineering ; Oceanography

Engineering, Marine ; Engineering, Ocean ; Oceanography

WOS:000774785600001

MDPI

2-s2.0-85125722935

Scopus

1.College of Ocean and Earth Sciences,Xiamen University,Xiamen,361102,China
2.Graduate Institute of Hydrological and Oceanic Sciences,College of Earth Sciences,National Central University,Taoyuan,320317,Taiwan
3.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
4.Department of Civil Engineering,Chung Yuan Christian University,Taoyuan,320314,Taiwan
5.Department of Naval Architecture & Ocean Engineering,United States Naval Academy,Annapolis,21402,United States
6.Department of Hydraulic and Ocean Engineering,National Cheng Kung University,Tainan,701401,Taiwan

Zhong，Yao Zhao,Chien，Hwa,Lin，Meng Yu,et al. On the Dependency of Bottom Drag and the Eddy Viscosity upon Flow Structure in the Coastal Boundary Layer[J]. Journal of Marine Science and Engineering,2022,10(3).

Zhong，Yao Zhao,Chien，Hwa,Lin，Meng Yu,Wargula，Anna,&Chen，Jia Lin.(2022).On the Dependency of Bottom Drag and the Eddy Viscosity upon Flow Structure in the Coastal Boundary Layer.Journal of Marine Science and Engineering,10(3).

Zhong，Yao Zhao,et al."On the Dependency of Bottom Drag and the Eddy Viscosity upon Flow Structure in the Coastal Boundary Layer".Journal of Marine Science and Engineering 10.3(2022).