| This paper mainly considers the point-vortex stability under the influence of an external periodic flow.The point-vortex system is transformed by Kelvin transformation and symplectic polar coordinates transformation,then the neighborhood of the vortex point is transformed to near the infinity point for discussion.The existence of the invariant curve under Poincare map is obtained by Moser’s invariant curve theorem,then the stability of the singularity of the point-vortex system was obtained by complex estimation of the coordinates. |
