Enhancement of turbulence through lateral spreading in a stratified-shear flow: Development and assessment of a conceptual model
Enhancement of turbulence through lateral spreading in a stratified-shear flow: Development and assessment of a conceptual model
复制标题
通过分层剪切流中的横向扩散增强湍流：概念模型的开发和评估
DOI：
10.1029/2011jc007484
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发表时间：
2012
影响因子：
--
通讯作者：
Fei Chen
中科院分区：
文献类型：
--
作者：
D. MacDonald;Fei Chen
[1]横向扩展过程对局部分层剪切湍流的影响的概念模型，并使用现场数据从快速扩展的近场区域的梅里马克河羽流进行评估。概念模型解决了与Kelvin-Helmholz巨浪沿着其旋转轴的拉伸相关的湍流动能的增加。一个无量纲的关系推导出两个适合的参数，包括一个参数表示的幅度下的混合没有扩散的情况下，和一个无量纲的时间尺度。为了使模型可行，这个时间尺度，代表开尔文-亥姆霍兹巨浪受到拉伸的时间段，应该与巨浪的演化时间尺度具有相同的数量级。从现场实验的观测数据被用来评估两个拟合参数，表示拉伸时间尺度的演化时间尺度在文献中报道的相同的顺序。此外，该模型的应用领域的数据减少了观察到的变化。我们的结论是，扩展是一个重要的机制，能够增强本地分层剪切湍流。
[1] A conceptual model for the impact of lateral spreading processes on local stratified-shear turbulence is presented and evaluated using field data from the rapidly spreading near-field region of the Merrimack River plume. The conceptual model addresses increases in turbulent kinetic energy associated with the stretching of a Kelvin-Helmholz billow along its rotational axis. A non-dimensional relationship is derived with two fit parameters, including a parameter representing the magnitude of mixing under the no spreading case, and a non-dimensional time scale. For the model to be viable, this time scale, representing the period of time that a Kelvin-Helmholz billow is subject to stretching should be of the same order as the evolution time scale for the billow. Observational data from field experiments are used to evaluate the two fit parameters, indicating a stretching time scale of the same order as evolution time scales reported in the literature. In addition, application of the model to the field data reduces observed variability. We conclude that spreading is an important mechanism capable of enhancing local stratified-shear turbulence.