Interaction of Multi-Vortex Rings

Abstract

Interaction of vortex rings simultaneously ejected from a number of orifices was experimentally studied by a flow visualization method. When three, four and six orifices were arranged equi-angularly in a circumference of a circle, a number of the vortex rings were ejected co-planarly through these orifices, and then they interacted with each other due to their mutual induced velocity. After cross-linking of the vortex filaments of these rings at the nearest portions of them, these filaments formed a larger vortex ring and a smaller one, and the larger ring continued its motion in the same direction with the original one, but the smaller one moved backward oppositely to the larger one. The virtual momentum was conserved during the interaction.