内孤立波破碎所致混合的实验研究

发布时间：2019-01-02 18:09

【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。
[Abstract]:In order to quantitatively analyze the mixing process of internal solitary wave breakup, a two-layer experiment of the first mode internal solitary wave breaking on a slope was carried out in a two-dimensional internal wave flume. Particle image velocimetry (PIV) was used to measure the propagation and breakage of internal solitary wave. The vorticity, turbulent kinetic energy and turbulent dissipation rate of the reflection process are calculated. The results show that the distribution characteristics of the internal waves with different amplitudes are very similar when they are broken on the slopes at different angles. There are two peaks in the time series of each element of the experiment, which occur at the time of nonlinear enhancement and breakup, respectively. The relationship between the turbulent dissipation rate and the amplitude of the internal solitary wave is obtained as follows: the turbulent dissipation rate of the small amplitude shows a second relation with the amplitude, and the dimensionless amplitude increases to 0.9 turbulence dissipation rate. The relationship between the slope angle and the slope angle is as follows: for the small amplitude internal wave slope angle increases, the degree of breakage decreases and the dissipation rate decreases, and when the amplitude is larger, there exists an angle to make the breakage degree maximum. The turbulent dissipation rate caused by breakage ranges from 10 ~ 7 to 10 4m2/s3, which is one order of magnitude larger than that of the observed internal solitary wave propagation interface and the topographic breakup of the internal tide.
【作者单位】：中国海洋大学海洋与大气学院;广东海洋大学海洋与气象学院;
【基金】：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
【分类号】：P731.24

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