Transient energy growth for the Lamb–Oseen vortex
Transient energy growth for the Lamb–Oseen vortex
复制标题
Lamb-Oseen 涡旋的瞬态能量增长
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
P. Brancher
中科院分区：
文献类型：
--
作者：
A. Antkowiak;P. Brancher
利用直接伴随技术研究了在Lamb-Oseen（高斯）涡中最佳诱导代数增长的无穷小流扰动的瞬态演化。这种最佳的扰动分析表明，兰姆-奥森涡允许强烈放大的动能为二维和三维扰动的方位波数m=1。在这两种情况下，经历最大增长的扰动最初在涡的外周处采取集中螺旋的形式，其在涡核内迅速激发弯曲波。在大波长的限制，最佳的扰动导致任意大的增长，通过一个原始的方案相结合的奥尔机制与涡诱导。
The transient evolution of infinitesimal flow disturbances which optimally induce algebraic growth in the Lamb–Oseen (Gaussian) vortex is studied using a direct-adjoint technique. This optimal perturbation analysis reveals that the Lamb–Oseen vortex allows for intense amplification of kinetic energy for two-dimensional and three-dimensional perturbations of azimuthal wavenumber m=1. In both cases, the disturbances experiencing the most growth initially take the form of concentrated spirals at the outer periphery of the vortex which rapidly excite bending waves within the vortex core. In the limit of large wavelengths, the optimal perturbation leads to arbitrarily large growths via an original scenario combining the Orr mechanism with vortex induction.