| 摘要: |
| 为定量分析内孤立波破碎的混合过程，本文在二维内波水槽中进行了两层流体第一模态内孤立波在斜坡上破碎的实验，运用粒子图像测速技术（PIV）测量内孤立波传播、破碎、反射过程的流场，计算涡度、湍动能和湍耗散率。结果表明不同振幅内波在不同角度斜坡上破碎时各个量的分布特征十分相似，各组实验各要素时间序列中均有两个峰值，分别发生于非线性增强和破碎时刻。得到破碎时湍耗散率与内孤立波振幅的关系为：较小振幅内波的湍耗散率与振幅呈2次关系，无因次振幅增大到0.9湍耗散率趋于不变；与斜坡角度的关系为：对于小振幅内波斜坡角度增大，破碎程度降低，耗散率减小；振幅较大时，存在一个角度使破碎程度最大。破碎引起的湍耗散率的量级在10-7到10-4m2/s3之间，比实测海洋中内孤立波传播界面和内潮遇地形破碎的湍耗散大1个量级。 |
| 关键词: 内孤立波破碎 PIV 湍耗散 涡度 湍动能 |
| DOI：10.11693/hyhz20150800218 |
| 分类号: |
| 基金项目:国家自然科学基金项目，41476001号；GLOD开放课题项目，GLOD1402号；中国海洋大学基本科研业务项目，201362011号。 |
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| AN EXPERIMENTAL STUDY ON MIXING INDUCED BY INTERNAL SOLITARY WAVE BREAKING |
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HUANG Peng-Qi1, CHEN Xu1, MENG Jing1, LI Min2, WAN Wei2
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1.Ocean University of China, College of Oceanic and Atmospheric Sciences, Qingdao 266100, China;2.Guangdong Ocean University, College of Ocean and Meteorology, Zhanjiang 524088, China
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| Abstract: |
| To understand the mixing that induced by internal solitary wave (ISW) breaking quantitatively, we conducted a 2-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 ε∝a2 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 10-7-10-4m2/s3, 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 |
