flow of [[fluid]]. Any [[spiral]] motion with closed [[Streamlines, streaklines and pathlines|streamlines]] is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex. The speed and rate of [[rotation]] of the fluid are greatest at the center, and decrease progressively with distance from the center. | flow of [[fluid]]. Any [[spiral]] motion with closed [[Streamlines, streaklines and pathlines|streamlines]] is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex. The speed and rate of [[rotation]] of the fluid are greatest at the center, and decrease progressively with distance from the center. |