Kármán涡街中旋涡三维变形的初步研究

Preliminary Study of the Three-Dimensional Deformation of the Vortex in Kármán Vortex Street

本文用涡动力学及LIA方法作为基本理论模型,数值研究了尾迹中孤立涡和细涡丝的三维演化规律。结果表明,圆柱分离尾迹中的旋涡存在三维不稳定性。卡门涡在尾迹平均流场中演化产生三维的类似于马蹄形-勺子形的流场结构。细涡丝在涡辫区的三维演化形成趋向流场最大拉伸变形方向的流向涡结构。

In this paper,the mechanism for three-dimensional evolution of the isolated Karman vortex and the thin vortex filament in a circular cylinder wake has been studied numerically using LIA method. The results show that the vortex motion is unstable for small three-dimensional disturbances in the separated wake of a circular cylinder. Karman vortex in the time-averaged wake flow field wolves into a horseshoe-spoon-like three-dimensional structure. The thin vortex filament deforms three-dimensionally in the braid and generates stream-wise vortex structures which incline to the region maximum deformation direction of the flow field.