think about an old tire rolling through paint. you'll see the same artifacts every revolution of the tire. the key idea is every cycle creates the same pattern.

so, you could have a mechanical system that hit the tube every /24th of a second, and you'd get some effect, but i think it would be hard to get the impact and recovery to be EXACTLY the same, or close enough you don't notice.

If you use sound to squeeze the tube, rather than pushing on it, the distortion and recovery are much more consistent, so you get the same pattern. I'd guess you don't have much control over where the drops actually appear. you'd have to wiggle the tube around on the speaker to get the right distortion.

It's a 'standing wave'.