研究業績

In classical hydrodynamics, a wake appearing behind a moving obstacle is characterized by a Reynolds number, the ratio of inertial forces to viscous forces. The Reynolds number is a quantity proportional to the characteristic length of the obstacle. As the Reynolds number increases, an unstable flow appears. A wake appears by considering obstacles using lasers in cold atom systems [1]. Furthermore, the Reynolds number in superfluids has also been suggested [2]. The Superfluid Reynolds number includes the critical velocity of the vortex generation and is not the ratio of inertial to viscous force as in the classical system. In this study, we study the size dependence of a plate obstacle in the Reynolds number by considering a wake in a 2D BEC system with a plate obstacle. Plate obstacle is very useful because it doesn’t need to consider density decay caused by gradient around the obstacle and size of the obstacle can be characterized only by the width of the plate. In this talk, we introduce the dynamics of the wake induced by the plate obstacle when its width is changed and discuss the future outlook. [1]T.W. Neely, et al. Phys. Rev. Lett. 104, 160401 (2010) [2]M.T. Reeves, et al. Phys. Rev. Lett. 114, 155302 (2015)