The Game of Passing-Through of a Pair of Vortex Rings

Abstract

When two similar vortex rings travel along the common axis of symmetry in the same direction, the game of passage of one vortex ring through the other was successfully realized both in air and in water. The phenomenon depends on the Reynolds number, Re , based on the initial traveling speed of vortex rings and the diameter of the ejecting orifice, and also depends on the time interval between two puffs of fluid by which the two vortex rings are produced. The region in the Re - T plane in which the game of passing-through is observed was experimentally determined both for air and for water, where T denotes a non-dimensional time interval. It was found that the region for water was smaller than that for air.