. . . "free-vortex" . "open vortex" . . "irrotational vortex" . "Vortices" . "vortex flow" . . . . "center" . "Vortex" . "air swirl" . . "vortex filaments" . . . . . "vortex" . "irrotational" . . . . "vortex storm" . "low-level circulation center" . . "suction vortices" . . "vortices" . "vortical" . . "gyre" . . "Irrotational vortices" . "vortex lines" . . . "Vortex#Irrotational vortices" . . . "vortex structure" . "swirl" . . "Vortex lines" . "eddies" . . . . "Vortex" . . . . . "Vorticity waves" . "vortical phenomena" .