Three-dimensional direct numerical simulation of wake transitions of a circular cylinder
Three-dimensional direct numerical simulation of wake transitions of a circular cylinder
复制标题
DOI：
10.1017/jfm.2016.446
复制
发表时间：
2016-07
影响因子：
3.7
通讯作者：
Hongyi Jiang;Liang Cheng;S. Draper;H. An;F. Tong
中科院分区：
文献类型：
--
作者：
Hongyi Jiang;Liang Cheng;S. Draper;H. An;F. Tong
本文介绍了在雷诺数（$Re$）至300范围内流过圆柱的三维（3D）直接数值模拟（DNS）。从模式A*（即具有大规模涡旋位错的模式A）到模式B的逐渐尾迹过渡过程在$Re$从230到260的范围内被很好地捕获。借助数值流动显示技术，对换模过程进行了详细的研究。研究发现，过渡过程中的B型结构是基于使辫状剪切层区域失稳的A型或A*型流向涡而形成的。对于跃迁范围内的每种情况，瞬态模式交换过程由位错和非位错周期组成。随着$Re$的增大，从纯A型结构触发位错并形成位错循环的难度增大，且每个位错阶段持续时间变短，导致A*型发生的概率不断减小，b型发生的概率不断增大，A*型的发生导致了较强的流动三维性。在大约$Re=265{-}270$处存在一个临界条件，在那里观察到最弱的流动三维，标志着从A*模态消失到出现越来越无序的B *模态结构的转变。
This paper presents three-dimensional (3D) direct numerical simulations (DNS) of flow past a circular cylinder over a range of Reynolds number ( $Re$ ) up to 300. The gradual wake transition process from mode A* (i.e. mode A with large-scale vortex dislocations) to mode B is well captured over a range of $Re$ from 230 to 260. The mode swapping process is investigated in detail with the aid of numerical flow visualization. It is found that the mode B structures in the transition process are developed based on the streamwise vortices of mode A or A* which destabilize the braid shear layer region. For each case within the transition range, the transient mode swapping process consists of dislocation and non-dislocation cycles. With the increase of $Re$ , it becomes more difficult to trigger dislocations from the pure mode A structure and form a dislocation cycle, and each dislocation stage becomes shorter in duration, resulting in a continuous decrease in the probability of occurrence of mode A* and a continuous increase in the probability of occurrence of mode B. The occurrence of mode A* results in a relatively strong flow three-dimensionality. A critical condition is confirmed at approximately $Re=265{-}270$ , where the weakest flow three-dimensionality is observed, marking a transition from the disappearance of mode A* to the emergence of increasingly disordered mode B structures.