Why Does a Water Stream's Pattern Change When Interrupted?

[RickRazor]

I observed something which I've never seen before. We left the tap open and the water stream was flowing in a particular pattern. When we placed a beaker under the water stream, the pattern disappeared. And the pattern itself was oscillating.

Here's the video link.

Below the the photos of the effect.

Is the pattern a standing wave? If yes, is it sound? And why does the pattern disappear when we place a beaker under it? In the later part of the video, you can see that the pattern itself is oscillating. Why is that happening?

 

[Pritamstar]

https://en.wikipedia.org/wiki/Plateau–Rayleigh_instability
It may help!

 

[Andy Resnick]

I observed something which I've never seen before. We left the tap open and the water stream was flowing in a particular pattern. When we placed a beaker under the water stream, the pattern disappeared. And the pattern itself was oscillating.

Here's the video link.

Is the pattern a standing wave? If yes, is it sound? And why does the pattern disappear when we place a beaker under it? In the later part of the video, you can see that the pattern itself is oscillating. Why is that happening?

Interesting video! A couple of comments:

1) your frame rate is very low as compared to the jet dynamics, certain aspects of the appearance (possibly the oscillations) can be related to this. If you have a strobe light, you can see if that (literally) clarifies the images.
2) When the jet impacts a surface, the pressure changes propagate at the speed of sound, much faster than the speed of water in the jet. Thus, certain effects (the location of jet breakup, for example) occur 'upstream' of where you think they should.