Kwon Woo Jin, Kim Joon Hyun, Seo Sang Won, Shin Y
Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea.
Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
Phys Rev Lett. 2016 Dec 9;117(24):245301. doi: 10.1103/PhysRevLett.117.245301. Epub 2016 Dec 7.
We report on the experimental observation of vortex cluster shedding from a moving obstacle in an oblate atomic Bose-Einstein condensate. At low obstacle velocities v above a critical value, vortex clusters consisting of two like-sign vortices are generated to form a regular configuration like a von Kármán street, and as v is increased, the shedding pattern becomes irregular with many different kinds of vortex clusters. In particular, we observe that the Stouhal number associated with the shedding frequency exhibits saturation behavior with increasing v. The regular-to-turbulent transition of the vortex cluster shedding reveals remarkable similarities between a superfluid and a classical viscous fluid. Our work opens a new direction for experimental investigations of the superfluid Reynolds number characterizing universal superfluid hydrodynamics.
我们报告了在扁球形原子玻色-爱因斯坦凝聚体中，从移动障碍物上脱落涡旋簇的实验观测结果。在障碍物速度v高于临界值时，由两个同号涡旋组成的涡旋簇会生成，形成类似冯·卡门街的规则构型，并且随着v的增加，脱落模式变得不规则，出现许多不同种类的涡旋簇。特别地，我们观察到与脱落频率相关的斯特劳哈尔数随v增加呈现饱和行为。涡旋簇脱落的从规则到湍流的转变揭示了超流体与经典粘性流体之间的显著相似性。我们的工作为表征通用超流动力学的超流雷诺数的实验研究开辟了一个新方向。
