If a vortex transports air in a spiral staircase fashion. Then there will be periods where the vortex flow will travel towards a reference object, and periods where it moves away from said object.
If you have a vortex underneath the length of a surface, then at one point the vortex is pushing air up towards and against the surface, and at another the vortex is moving down and away.
That means that a vortex traveling down a surface can impart a cyclical up and down momentum on that surface if the vorticity is strong enough. The upward momentum of the vortex pushing up then the downward momentum pulling back down.
https://www.youtube.com/watch?v=1I2SlU0SYsQ
If a vortex transports air in a spiral staircase fashion. Then there will be periods where the vortex flow will travel towards a reference object, and periods where it moves away from said object.
If you have a vortex underneath the length of a surface, then at one point the vortex is pushing air up towards and against the surface, and at another the vortex is moving down and away.
That means that a vortex traveling down a surface can impart a cyclical up and down momentum on that surface if the vorticity is strong enough. The upward momentum of the vortex pushing up then the downward momentum pulling back down.
https://www.youtube.com/watch?v=1I2SlU0SYsQ
(post is archived)