On the relation between linear stability analysis and mean flow properties in wakes
On the relation between linear stability analysis and mean flow properties in wakes
复制标题
线性稳定性分析与尾流平均流动特性的关系
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
J. Wesfreid
中科院分区：
文献类型：
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作者：
B. Thiria;G. Bouchet;J. Wesfreid
在最近关于尾流稳定性的研究中，已经观察到，应用于平均流而不是基本流的简单线性稳定性分析可以给出全局模式选择频率的准确预测，尽管这些现象是强非线性的。本文研究了Re=150时圆柱尾流的定常解（所谓的基本态）与非定常解之间的过渡态。我们表明，由于强非线性效应的全球频率作为时间的函数的移位，可以解释由不稳定性的增长引起的连续平均流校正。我们表明，在此瞬态制度，作为时间的函数的平均状态起着瞬时的基本状态的作用，在其上的全球频率可以线性地确定。
In recent studies on wake stability, it has been observed that a simple linear stability analysis applied to the mean flow instead of the basic flow, could give an accurate prediction of the global mode selected frequency, although these phenomena are strongly non-linear. In this letter, we study the transient regime between the stationary (so called basic state) and unstationary solutions of the wake of a circular cylinder at Re=150. We show that the shift of the global frequency as a function of time due to strong non-linear effects, can be interpreted by a continuous mean flow correction induced by the growth of the instability. We show that during this transient regime, the mean state as a function of time plays the role of an instantaneous basic state on which the global frequency can be determined linearly.