Microsoft Word - 6--黄鹏起_new_.doc

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1 47 3 Vol.47, No OCEANOLOGIA ET LIMNOLOGIA SINICA May, 016 * ( ; ),, (PIV),,, :, 0.9 ; :,, ;, m /s 3, 1 ; PIV; ; ; P731.4 doi: /hyhz ,, (, 01) (Garrett et al, 007),,, (Ledwell et al, 000; Nikurashin et al, 010; Klymak et al, 01),,,,,, Ivey (1989),, 0.Helfrich(199),, 15%±5%Michallet (1999) Ivey (1989), L W L S, L W /L S =0.5 5%; L W /L S 0.5, (014),,,,, (010), 0.18; Li (015) *, ; GLOD, GLOD140 ;, , paangheiwong@16.com :,, chenxu001@ouc.edu.cn : , :

2 534 47, Klymak (01), Hawaii Ridge, m /s 3, 1 Moum (003) Oregon 0, m /s 3,, Klymak (008) Thorpe Kaena Ridge m /s 3, PIV,,, 1, 1 3m 0.15m 0.3m, x, z θ, ρ 1 ρ, h 1 h, H 1 Fig.1 Schematic diagram of experimental design 1, 1, 4 PIV, 50μm :, 4 η cm 9cmCCD, , 50 /s, 0.0s, 1, 4 40cm 表 1 实验条件 Tab.1 Experimental conditions θ( ) ρ /ρ 1 h /H PIVlab( PIV, Thielicke et al, 014):, FFT window deformation, 16 16,,,,, (direct method) ui ui u u i j ee ij ij, (1) x j xj xj x i, u i, x i x j ( i j 1 3, ), υ cm /s (10 C, g/cm 3 ), PIV, (1) (Doron et al, 001) u1 u3 u1 u3 3 u3 u1 4 x1 x3 x1 x3 4 x1 x 3 () Moum (003),, (1) 15 u1 x3 15 u3 x3, (3), (4)

流体与波速同向流动, 下层流体反向流动, 反射波反之图 4b 垂直速度时间序列则呈现明显的波前下降流波后上升流特点实验结果实验中采集的图像如图所示, 其中 a 为实验塌陷高度 cm, b 为实验 3 塌陷高度 5cm, c 为实验 4 塌陷高度 9cm 的图像, 1 4 分别为内孤立波传播等密度面变陡破碎冲击水上涌的过程图4 Fig.

3 3期黄鹏起等: 内孤立波破碎所致混合的实验研究 3.1 或是 15 u1 u3 4 x3 x3 (5) 湍动能(TKE)由下式计算 1 Ek ui ui (6) u w 涡度 vort (此处 u w 分别为水平和垂直瞬 z x 时速度)可由 PIVlab 计算流速同时导出速度场分析所有实验图像得到速度场, 可知所有实验中的流速大小在 0 10cm/s 之间从图 4a 可以看到入射波的流动可用界面处的剪切描述: 入射波上层流体与波速同向流动, 下层流体反向流动, 反射波反之图 4b 垂直速度时间序列则呈现明显的波前下降流波后上升流特点实验结果实验中采集的图像如图所示, 其中 a 为实验塌陷高度 cm, b 为实验 3 塌陷高度 5cm, c 为实验 4 塌陷高度 9cm 的图像, 1 4 分别为内孤立波传播等密度面变陡破碎冲击水上涌的过程图4 Fig.4 视场 x=cm 断面速度时间序列 Velocity time series at x=cm profile in the field of view a: 水平速度, b: 垂直速度从速度的空间分布图(图 5)观察到这一相对对称的流动于波后近底部处首次发生变形, 波谷下速度沿斜坡向下, 波后则向上, 导致逆压力梯度的产生; 随后内波的等密度面发生翻转呈 Z 形, 这是因为右实验 4 原始照片上方的水体继续向右运动, 而波面以上被斜坡下部 Images of Experiments 4 阻挡的水体则向左挤压, 致使原本在该处波面以下图 Fig. 分析斜坡左侧断面时间序列, 拟合得到塌陷高的水体向右沿斜板向上运动, 此时波前变缓波后变度 η 与内孤立波振幅 a 关系如图 3, 可看出两者呈良陡, 导致了波形的破碎压力梯度增大, 波后垂向速好的线性正相关度增大, 变得不稳定, 重流体被抬升到轻流体中, 波后产生强逆时针涡旋(图 5a, x=15cm 斜坡上方处), 反过来又将轻的粒子带到波后的下方; 图 5b 中可以看到破碎过程的继续发展, 涡旋强度和范围增大, 斜板右上方水体仍向右运动但速度减小该部分水体随后受到斜板阻碍, 产生向左的速度上层左侧的水体则已经作为反射波向左运动了, 此时的流场可用上层的离岸流和下层沿斜坡向上的强底流描述, 破碎区域中出现向右运动速度的极大值, 运动方向较为杂乱, 冲击水的运动速度很大; 冲击水在斜坡上运动达到最高点, 反射波离开视场后, 整个场流速都变得很小图3 Fig.3 塌陷高度 η 与入射波振幅 a 关系 Relation between collapse height and incident wave amplitude 3. 湍耗散使用上述脉动速度空间分布的直接法求出每隔

536 47 3 4 9cm,,, 4 3, 3 ( cm),,, 10 5 m /s 3 5, Fig.5 Two typical patterns of spatial distribution of velocity field during breaking; the background contour is vorticity a 与 b 时间间隔为.5s 0.

4 cm,,, 4 3, 3 ( cm),,, 10 5 m /s 3 5, Fig.5 Two typical patterns of spatial distribution of velocity field during breaking; the background contour is vorticity a 与 b 时间间隔为.5s 0.5s, ε vort TKE m /s 3, 6a 3,,, 1s,,,,, 6b,,,, a, b 3, ;, : 4, 4 89cm,,, 6 ε vort TKE Fig.6 Time series of normalized maximum turbulence dissipation rate, square vorticity, and turbulence kinetic energy (TKE) a: 实验 4 塌陷高度 5cm; b: 实验 3 塌陷高度 9cm 表破碎时不同斜坡角度不同振幅内波最大湍耗散率 Tab. Maximum ε at different slope angle and different internal wave amplitude during breaking - Exp-θ( ) (cm) (10 5 m /s 3 ) (cm) (10 5 m /s 3 ) a, 7, 3 : 1 ; George (1991),, ,,,

5 3 : 537 PIVlab 16 16, 3mm 3mm,,,,, 7 a: ε, b: TKE c: Fig.7 Spatial distribution at the peak time 左 : 峰值时刻 1, 右 : 峰值时刻 a: ε; b: TKE; c: vorticity Left panel: Peak time 1; Right panel: Peak time, (/) 8, 8a 0.9,, 0.9,,,,, 9 a c, b,, ( 8 14s), 7s,,, Moum (003) Klymak (008) 1,,, 1.05g/cm 3,,, 8 ε(a) TKE(b) vort (c) Fig.8 The fitted line of dimensionless amplitude vs maximum ε(a), TKE(b), and square vorticity(c)

6 538 47,, ;.8,,, 9 3 η=9cm, x=9.8cm Fig.9 The time series of turbulence dissipation rate when η=9cm, x=9.8cm in Experiment 3 a: 水平, b: 垂直, c: 水平 + 垂直脉动速度计算结果,,,,, ;,,,, 4, : (1),,,, Kelvin-Helmholtz (), 3,,,, (3) m /s 3, m /s 3 1 (4), 0.9,,,, 014.., 38(10): ,,, 010.., 41(6): ,, 01.., 9(6): 9 Doron P, Bertuccioli L, Katz J et al, 001. Turbulence characteristics and dissipation estimates in the coastal ocean bottom boundary layer from PIV data. Journal of Physical Oceanography, 31(8): Garrett C, Kunze E, 007. Internal tide generation in the deep ocean. Annual Review of Fluid Mechanics, 39(1): George W K, Hussein H J, Locally axisymmetric turbulence. Journal of Fluid Mechanics, 33: 1 3 Helfrich K R, 199. Internal solitary wave breaking and run-up on a uniform slope. Journal of Fluid Mechanics, 43: Ivey G N, Nokes R I, Vertical mixing due to the breaking of critical internal waves on sloping boundaries. Journal of Fluid Mechanics, 04: Klymak J M, Legg S, Alford M H et al, 01. The direct breaking of internal waves at steep topography. Oceanography, 5(): Klymak J M, Pinkel R, Rainville L, 008. Direct breaking of the internal tide near topography: Kaena Ridge, Hawaii. Journal of Physical Oceanography, 38(): Ledwell J R, Montgomery E T, Polzin K L et al, 000. Evidence for enhanced mixing over rough topography in the abyssal ocean. Nature, 403(6766): Li Q, Xu Z H, Yin B S et al, 015. Modeling the interaction of an internal solitary wave with a sill. Acta Oceanologica Sinica, 34(11): 3 37 Michallet H, Ivey G N, Experiments on mixing due to internal solitary waves breaking on uniform slopes. Journal of Geophysical Research: Oceans ( ), 104(C6): Moum J N, Farmer D M, Smyth W D et al, 003. Structure and generation of turbulence at interfaces strained by internal solitary waves propagating shoreward over the continental shelf. Journal of Physical Oceanography, 33(10): Nikurashin M, Ferrari R, 010. Radiation and dissipation of internal waves generated by geostrophic motions impinging on small-scale topography: Theory. Journal of Physical

7 3 : 539 Oceanography, 40(5): Thielicke W, Stamhuis E J, 014. PIVlab towards user-friendly, affordable and accurate digital particle image velocimetry in MATLAB. Journal of Open Research Software, (1): e30 AN EXPERIMENTAL STUDY ON MIXING INDUCED BY INTERNAL SOLITARY WAVE BREAKING HUANG Peng-Qi 1, CHEN Xu 1, MENG Jing 1, LI Min, WAN Wei (1. Ocean University of China, College of Oceanic and Atmospheric Sciences, Qingdao 66100, China;. Guangdong Ocean University, College of Ocean and Meteorology, Zhanjiang 54088, China) Abstract To understand the mixing that induced by internal solitary wave (ISW) breaking quantitatively, we conducted a -dimensional experiment on ISW in an internal wave tank in different amplitudes and slopes. Particle Image Velocimetry (PIV) was employed to visualize the velocity field of ISW during propagating, breaking, and reflecting. Vorticity, dissipation rate ε, and turbulence kinetic energy (TKE) were calculated. Results show in overall similar features among these parameters in different amplitudes a and slopes, showing two peaks in maximum square vorticity, TKE, and ε time series. The first peak appeared when nonlinearity boosting and the second at the breaking. We obtained εa for ISW of relatively small amplitude, and for large amplitude ISW, ε increased slowly and stayed at a certain point. For incident wave of ISW of relatively small amplitude, a larger slope lead to weaker breaking and smaller ε, while for that of large amplitude there occurred a slope at which most intense breaking took place. The dissipation rate measured ranged m /s 3, which is a magnitude larger than turbulence dissipation rate measured in real oceanic ISW interface and internal tide breaking. Key words internal wave breaking; PIV; turbulent dissipation; vorticity; turbulence kinetic energy

Microsoft Word - 2--王伟_new_.doc

Microsoft Word - 2--王伟_new_.doc 47 3 Vol.47, No.3 016 5 OCEANOLOGIA ET LIMNOLOGIA SINICA May, 016 * 1 1 1 1 (1. 66100;. 66590) KdVmKdV, Fluent,,,,, :, ;,, ;,, Fluent; ; ; ; P751 doi: 10.11693/hyhz0150600165,,,, (, 001), (Osborne et al,