气候变化领域集成服务门户(CCPortal): A Turbulence-Resolving Numerical Investigation of Wave-Supported Gravity Flows

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DOI	10.1029/2019JC015220
	A Turbulence-Resolving Numerical Investigation of Wave-Supported Gravity Flows
	Yue L.; Cheng Z.; Hsu T.-J.
发表日期	2020
ISSN	21699275
卷号	125 期号:2
英文摘要	Wave-supported gravity flows (WSGFs) have been identified as a key process driving the offshore delivery of fine sediment across continental shelves. However, our understanding on the various factors controlling the maximum sediment load and the resulting gravity current speed remains incomplete. We adopt a new turbulence-resolving numerical model for fine sediment transport to investigate the formation, evolution, and termination of WSGFs. We consider the simplest scenario in which fine sediments are supported by the wave-induced fluid turbulence at a low critical shear stress of erosion over a flat sloping bed. Under the energetic wave condition reported on the Northern California Coast with a shelf slope of 0.005, simulation results show that WSGFs are transitionally turbulent and that the sediment concentration cannot exceed 30 kg/m3 (g/L) due to the attenuation of turbulence by the sediment-induced stable density stratification. Wave direction is found to be important in the resulting gravity current intensity. When waves are in cross-shelf direction, the downslope current has a maximum velocity of 1.2 cm/s, which increases to 2.1 cm/s when waves propagate in the along-shelf direction. Further analysis on the wave-averaged momentum balance confirms that when waves are parallel to the slope (cross-shelf) direction, the more intense wave-current interaction results in larger wave-averaged Reynolds shear stress and thus in a smaller current speed. Findings from this study suggest that the more intense cross-shelf gravity current observed in the field may be caused by additional processes, which may enhance the sediment-carrying capacity of flow, such as the ambient current or bedforms. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	intermittently turbulent flow; turbulence-resolving numerical simulation; wave direction; wave-supported gravity flows
语种	英语
来源期刊	Journal of Geophysical Research: Oceans
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187003
作者单位	Center for Applied Coastal Research, Civil and Environmental Engineering, University of Delaware, Newark, DE, United States; Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Convergent Science, Inc., Madison, WI, United States
推荐引用方式 GB/T 7714	Yue L.,Cheng Z.,Hsu T.-J.. A Turbulence-Resolving Numerical Investigation of Wave-Supported Gravity Flows[J],2020,125(2).
APA	Yue L.,Cheng Z.,&Hsu T.-J..(2020).A Turbulence-Resolving Numerical Investigation of Wave-Supported Gravity Flows.Journal of Geophysical Research: Oceans,125(2).
MLA	Yue L.,et al."A Turbulence-Resolving Numerical Investigation of Wave-Supported Gravity Flows".Journal of Geophysical Research: Oceans 125.2(2020).