Initiation of drop velocity oscillations during their fall in a vertically sheared flow with embedded velocity fluctuation
Initiation of drop velocity oscillations during their fall in a vertically sheared flow with embedded velocity fluctuation
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在具有嵌入速度波动的垂直剪切流中下落期间，液滴速度振荡的启动
DOI：
10.1080/03091929408226577
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发表时间：
1994
影响因子：
1.3
通讯作者：
A. Khain
中科院分区：
文献类型：
--
作者：
M. Pinsky;A. Khain
摘要研究了水平剪切流中嵌入“冻结”正弦速度脉动的液滴落下问题。结果表明，即使在这种简单的情况下，液滴的轨迹和速度也显得非常复杂。流动中的波动“冻结”，使液滴集中在某些平衡点，这些平衡点位于相对于波动阶段的某些空间位置。这些点之间的距离取决于起伏的“波长”。因此，“冻结”湍流可导致某些区域内水滴(特别是小水滴)浓度的增加，以及这些区域之间水滴浓度的降低。在剪切流中，在一定的滴落距离下，液滴的运动特性发生了质的变化：由于存在鞍结点分叉，液滴速度(和轨迹)会发生振荡。这一临界下落距离和振荡参数取决于液滴质量和流动参数：风的切变值、振幅和速度。
Abstract Drops’ fall in the horizontal sheared flow with an embedded ‘‘frozen'’ sinusoidal velocity fluctuation is studied. It is shown that drops’ trajectory and velocity appear to be very complicated even in this simple case. The fluctuation ‘‘frozen'’ in the flow concentrates droplets in certain points of equilibrium, located spatially in certain places relative to the phase of the fluctuation. The distance between these points depends on the ‘‘wavelength'’ of the fluctuation. Thus, ‘‘frozen'’ turbulence can lead to an increase of the concentration of water drops (especially small droplets) in certain zones and to a decrease of drop concentration between these zones. At a certain drop fall distance in a sheared flow a qualitative change of the drop motion character takes place: due to the saddle-node bifurcation drop velocity (and trajectory) oscillations are generated. This critical fall distance and parameters of oscillations depend on the drop mass and flow parameters: the wind shear value, amplitud...