虚拟体法数值模拟双圆柱强迫振荡系统

Simulation on forced system of two cylinders using virtual boundary method

用虚拟体方法研究了均匀流及尾流中圆柱横向振荡的流动特征。单圆柱结果与相关试验吻合,得到了“锁定”区域,发现涡量跳跃现象。对小间距双圆柱的数值模拟发现,在“锁定”区域附近随激励频率的增加流场特征会出现若干显著的变化,包括涡量的跳跃,涡模态的改变,正负涡量带的形成和消失。在大间距情况下发现下游圆柱的振荡对上游尾涡脱落没有明显的影响,下游圆柱尾流场没有发现“锁定”现象。

Flow field of a circular cylinder oscillating in a uniform flow or in a wake was investigated using currently modified virtual boundary method. Results of a single cylinder show reasonable agreements with experiments. The forced system of two cylinders with small spacing is studied and fancy flow characteristics are observed. Vortex switch and change of vortex modes are well observed. Vorticity bands are formed and disappeared with increasing the excitation frequencies. In the case of large spacing, the upstream cylinder sheds vortex as no downstream one oscillating in the wake. No distinct “ lock-on” response is found for the downstream cylinder.