The butterfly effect and the transition to turbulence in a stratified shear layer
The butterfly effect and the transition to turbulence in a stratified shear layer
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DOI：
10.1017/jfm.2022.985
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发表时间：
2022-12
影响因子：
3.7
通讯作者：
Chih-Lun Liu;A. Kaminski;W. Smyth
中科院分区：
文献类型：
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作者：
Chih-Lun Liu;A. Kaminski;W. Smyth
在稳定分层的剪切层中，多种相互竞争的不稳定性对初始条件的微小变化产生敏感性，通常称为蝴蝶效应（如扑翼可能改变天气）。三个合奏的15个模拟混合事件，相同的，但对初始状态的小扰动，被用来探索的路线，湍流的差异，最大湍流水平和总量和效率的混合完成每个事件。比较表明，在初始状态的一个小的变化改变的强度和时间的主要开尔文-亥姆霍兹不稳定性，次谐波配对不稳定性和各种三维二次不稳定性，导致湍流。的效果是最大的，但不限于，参数政权配对和三维二次不稳定性是在激烈的竞争。可以加速或阻止配对;最大湍流动能可以变化高达4.6倍，通量Richardson数变化12%-15%，净混合变化2倍。
Abstract In a stably stratified shear layer, multiple competing instabilities produce sensitivity to small changes in initial conditions, popularly called the butterfly effect (as a flapping wing may alter the weather). Three ensembles of 15 simulated mixing events, identical but for small perturbations to the initial state, are used to explore differences in the route to turbulence, the maximum turbulence level and the total amount and efficiency of mixing accomplished by each event. Comparisons show that a small change in the initial state alters the strength and timing of the primary Kelvin–Helmholtz instability, the subharmonic pairing instability and the various three-dimensional secondary instabilities that lead to turbulence. The effect is greatest in, but not limited to, the parameter regime where pairing and the three-dimensional secondary instabilities are in strong competition. Pairing may be accelerated or prevented; maximum turbulence kinetic energy may vary by up to a factor of 4.6, flux Richardson number by 12 %–15 % and net mixing by a factor of 2.