Abstract
This paper describes a flowfield produced by a circular vortex ring travelling across a thin circular cylinder. The flowfield was investigated by using the smoke visualization method. A pair of vortices was found to be induced by boundary layer separation from the cylinder surface as the vortex ring travelling across the cylinder. These induced vortices were ejected from a circulating region of the main ring. According to pictures taken at various locations. it was conjectured that induced vortices have a kind of horseshoe shape. After travelling across a thin cylinder the main vortex ring underwent distortion, that is. the ring performed such a motion as an elliptical vortex ring. We studied the effect of the diameter of the circular cylinder on the motion of the ring. Some critical values of the diameter to define the mode of vortex motion were suggested to exist.
