Influence of Langmuir circulations on turbulence in the bottom boundary layer of shallow water

doi:10.1017/jfm.2018.883

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	Influence of Langmuir circulations on turbulence in the bottom boundary layer of shallow water
	Deng BQ 2,3; Yang ZX(杨子轩)1,2,3; Xuan AQ 2,3; Shen L 2,3
刊名	JOURNAL OF FLUID MECHANICS
	2018-12-19
卷号	861 页码:275-308
关键词	turbulence simulation turbulent boundary layers wave-turbulence interactions
ISSN号	0022-1120
DOI	10.1017/jfm.2018.883
通讯作者	Shen, Lian(shen@umn.edu)
英文摘要	Langmuir circulations (LCs) generated by the interaction between wind-driven currents and surface waves can engulf the whole water column in neutrally stratified shallow water and interact with the turbulence in the bottom boundary layer. In this study, we perform a mechanistic study using wall-resolved large-eddy simulations (LES) based on the Craik-Leibovich equations to investigate the effects of LCs on turbulence statistics in the bottom half of shallow water. The highest. Reynolds number considered in this paper, Re-tau = 1000, is larger than the values considered in wall-resolved LES studies of shallow-water Langmuir turbulence reported in literature. The logarithmic layer is diagnosed based on a plateau region in the profile of a diagnostic function. It is found that the logarithmic layer disrupted at Re-tau = 395 reappears at Re-tau = 1000, but the von Karman constant is slightly different from the traditional value 0.41. To study the effects of LCs on turbulence statistics, LCs are extracted using streamwise averaging. The velocity fluctuations u'(i) are decomposed into a LC-coherent part u(i)(L) and a residual turbulence part u(i)(T). It is found that the profiles of LC-coherent. Reynolds shear stress -< u(L)v(L)> obtained at various Reynolds numbers are close to each other in the water-column coordinate y/h, with h being the half-water depth. As the Reynolds number (or, by definition, the ratio between the outer and inner length scales) increases, the influence of LCs on the near-bottom momentum transfer is reduced, which is responsible for the reappearance of the logarithmic layer. At all of the Reynolds numbers under investigation, the peaks of < u(L)u(L)> are collocated in the water-column coordinate y/h, while those of < u(T)u(T)> are collocated in the inner-scale coordinate y/(v/u(tau)). Due to the increase in the distance between the peaks of < u(L)u(L)> and < u(T)u(T)> with the Reynolds number, the profile of < u' u'> forms a bimodal shape at Re-tau 700 and 1000.
分类号	一类/力学重要期刊
资助项目	Office of Naval Research ; National Science Foundation ; Minnesota Sea Grant
WOS关键词	LARGE-EDDY SIMULATION ; DIRECT NUMERICAL-SIMULATION ; CHANNEL FLOW ; MIXED-LAYER ; VORTEX FORCE ; PIPE-FLOW ; WALL ; OCEAN ; WIND ; SUPERCELLS
WOS研究方向	Mechanics ; Physics
语种	英语
WOS记录号	WOS:000454172000001
资助机构	Office of Naval Research ; National Science Foundation ; Minnesota Sea Grant
内容类型	期刊论文
源URL	[http://dspace.imech.ac.cn/handle/311007/78958]
专题	力学研究所_非线性力学国家重点实验室
作者单位	1.Chinese Acad Sci, State Key Lab Nonlinear Mech, Inst Mech, Beijing 100190, Peoples R China 2.Univ Minnesota, Dept Mech Engn, 111 Church St SE, Minneapolis, MN 55455 USA; 3.Univ Minnesota, St Anthony Falls Lab, Minneapolis, MN 55455 USA;
推荐引用方式 GB/T 7714	Deng BQ,Yang ZX,Xuan AQ,et al. Influence of Langmuir circulations on turbulence in the bottom boundary layer of shallow water[J]. JOURNAL OF FLUID MECHANICS,2018,861:275-308.
APA	Deng BQ,杨子轩,Xuan AQ,&Shen L.(2018).Influence of Langmuir circulations on turbulence in the bottom boundary layer of shallow water.JOURNAL OF FLUID MECHANICS,861,275-308.
MLA	Deng BQ,et al."Influence of Langmuir circulations on turbulence in the bottom boundary layer of shallow water".JOURNAL OF FLUID MECHANICS 861(2018):275-308.