Turbulence within inertia‐buoyancy balanced axisymmetric intrusions
Turbulence within inertia‐buoyancy balanced axisymmetric intrusions
复制标题
惯性浮力平衡轴对称侵入体中的湍流
DOI：
10.1029/95jc00274
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发表时间：
1995
影响因子：
--
通讯作者：
J. Imberger
中科院分区：
文献类型：
--
作者：
C. Lemckert;J. Imberger
从两个详细的现场实验的数据被用来调查内的湍流惯性浮力平衡，轴对称侵入重力流进入近静止的分层水体。侵入体是由安装在不同淡水水库内的高能点源气泡羽流系统产生的，并用显微结构剖面仪记录了混合活动。在接近气泡羽流的地方，发现侵入物非常动荡。湍流活动的侵入体内观察到衰减最迅速的侵入核心，但剪切在上，下边界的侵入体保持在这些地区的湍流很长一段距离。结果表明，湍流开始时的长度尺度等于内部产生的剪切的最大可持续倾覆长度，因此湍流弗劳德数接近1。随着侵入体远离生成区域，弗劳德数保持接近1，但雷诺数随距离而减小;侵入体产生的剪切因此维持了活跃的湍流场，尽管长度尺度不断减小。
Data from two detailed field experiments were used to investigate the turbulence within inertia-buoyancy balanced, axisymmetric intrusive gravity currents entering nearly quiescent stratified water bodies. The intrusions were generated by energetic point source bubble plume systems installed within different freshwater reservoirs, and the mixing activity was recorded with microstructure profilers. Close to the bubble plume, the intrusions were found to be very turbulent. The turbulent activity within the intrusions was observed to decay most rapidly in the intrusion core, but the shear at the upper and lower boundaries of the intrusions maintained the turbulence in these regions for a long distance. The results showed that the turbulence began with a length scale equal to the maximum sustainable overturn length for internally generated shear and hence a turbulent Froude number near unity. As the intrusions moved away from the generation region, the Froude number remained near unity, but the Reynolds number decreased with distance; the shear generated by the intrusion thus sustained an active turbulence field, albeit with ever decreasing length scales.