Mixing Layer Dynamics in Separated Flow Over an Estuarine Sill with Variable Stratification
Mixing Layer Dynamics in Separated Flow Over an Estuarine Sill with Variable Stratification
复制标题
具有可变层结的河口基台分离流中的混合层动力学
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
C. Chickadel
中科院分区：
文献类型：
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作者：
PDXScholar PDXScholar;S. Talke;A. Horner‐Devine;C. Chickadel
[1]我们调查的生成的混合层的分离流背后的一个河口的窗台（高度H <$4米）在斯诺霍米什河，华盛顿州的相干结构，使用远程和原位传感的一个更大的调查的一部分。在落潮增加的过程中，深度d和层结减小，并形成一个剪切流区域，其特征是湍流动能的增加。的速度和声学后向散射的配置文件表现出相干波动的顺序为0.1 Hz，并用于定义的混合层的边界。混合层宽度及其嵌入的相干结构的变化是由归一化的门槛高度H/d和使用门槛上的流动深度定义的批量理查森数Rih的变化引起的。卷吸ET和混合层扩展角随着层化和整体Richardson数的减小而增大;由于底坎对流动的阻挡，该关系式参数化为ET = 0.07Rih−0.5，在约0.1 0.8时有效。
[1] We investigate the generation of a mixing layer in the separated flow behind an estuarine sill (height H ∼ 4 m) in the Snohomish River, Washington as part of a larger investigation of coherent structures using remote and in situ sensing. During increasing ebb flows the depth d and stratification decrease and a region of sheared flow characterized by elevated production of turbulent kinetic energy develops. Profiles of velocity and acoustic backscatter exhibit coherent fluctuations of order 0.1 Hz and are used to define the boundaries of the mixing layer. Variations in the mixing layer width and its embedded coherent structures are caused by changes to both the normalized sill height H/d and to a bulk Richardson number Rih defined using the depth of flow over the sill. Entrainment ET and the mixing layer expansion angle increase as stratification and the bulk Richardson number decrease; this relationship is parameterized as ET = 0.07Rih−0.5 and is valid for approximately 0.1 0.8 due to blocking of flow by the sill.