CONTOUR DYNAMICS FOR THE MOTION OF MULTIPLE RING VORTICES^*

This paper generalizes the contour dynamics for single ring vortices to that for multiple ring vortices, wherein six sets of numerical computation are performed. The phenomenon of the counterclockwise loop of a moving vortex is clearly shown in the computational results and the asymmetric change with time of the vortex structure may serve as a precursor for the phenomenon. Besides, we also discuss the dependence of the motion direction of a vortex upon the degree of its contour denseness, and the dependence of the westward component of vortex motion upon its asymmetric structure. The results are fairly consistent with those of previous dynamical analyses and numerical experiments.