The Weird Science of Tossing Stones Into a Lake

Interoperable writes "Researchers in Spain and the Netherlands add another piece to a centuries-old puzzle in physics: the dynamics of an object falling into water. This common occurrence has a complex anatomy that includes a thin 'crown splash' around the perimeter of the impact, a deep cavity of air following the impactor, and a high, narrow jet of water that results from the collapse of the cavity. The new research, recently published in Physical Review Letters, demonstrates that airflow through the neck of the collapsing cavity reaches supersonic speeds despite low relative pressures between the air in the cavity and ambient pressure. Such an effect has no analogue in aerospace engineering or other sciences because of the highly dynamic nature of the collapsing nozzle structure." It's funny that the APS wants to charge non-subscribers $25 to download what is available for free on the arXiv.

Comments

On The West Coast...

[__aaclcg7560]

The only way to appreciate the science of tossing stones into a lake is to be stoned yourself.

Make you a deal...

[djupedal]

If you promise not to mess with the nature of my nozzle's highly dynamic collapsing nozzle-structure, I won't mess with yours - unless you want me to, of course, in which case I would expect to be able to count on reciprocity.

I think that's only fair, I mean, especially given that we just met and all. Let's just hope your nozzle hasn't been anywhere unseemly lately. I hate unseemly nozzles and I have no use for any with a rather static collapsing nozzle-structure, as I'm sure most people do. yuck....

Looks like we elected the wrong guy

[Trepidity]

Imagine what the U.S.'s technology leadership could've been like if we had put a President in the White House who truly understood this kind of cutting-edge science.

How ARXIV and PRL work together

[imsabbel]

Just some pieces of info for people who might not know:

Nowadays, all the major publishers dont have an issue if you post a prepring on arxiv, prl included.
If you want to get a preprint out, the procedure is as follows:

1) You put something on arxiv and submit it to PRL.
2) After a few weeks/months, you get your referee reports.
3) Then you revise it, and update your arxiv version.
4) Paper gets accepted. Paper is entering the editorial process, and you get proofs.
  -> at this point, APS has contributed to the paper. The specific version proofed by PRL can no longer be uploaded to ARXIV /etc.
5) Final corrections, ready to print.

Nowadays, the proof and setting part is relatively minor. Most likely you will have written it in RevTex, and have PDF figures, so its an no issue.
But they still allow you to send them the text in word and the figures in phyical form (ink drawing, whatever), if you are really interested in it not getting published quickly.

So for most issues, a paper on Arxiv might be 99.9% identical to the final published paper, and only diiffer by the editorial issues. But you cannot know it. It might also represent a state from before the peer review.

Testing Process

[KneelBeforeZod]

I'd love to see the testing process for this.

Tries 1 - 100

1. Plop
2. Plunk
3. Plunk
4. Bloop
5. Plunk ....

Give me a grant!

Viscosity Changes the Sound Too

[Tisha_AH]

My younger brother discovered a key principle of the viscosity of fluids when he was 12 years old. He and his friend decided to drop a gigantic boulder down the center hole of an outhouse, they were standing over the "opening" to see the effect.

I imagine the sound was much "deeper" but their screams were really high.

It was a 2 mile walk to the nearest running water for them, our camping trips were never the same after that.

Re:Viscosity Changes the Sound Too

[mikael]

A similar event happened during the construction of the London flood barrier. For some reason, a large amount of material had to be dumped into the river Thames. This might have been cement or just rubble for part of the underground foundations. It was anticipated that this process might generate some sort of pressure wave that would travel at high speed through the water. Thus a warning was given not to be in the river or close any storm drains at this time. Unfortunately, this warning was not received by a particular tenant of an old apartment block which had one end of their combined storm drain/sewer overflow submerged in the river. Minutes after the construction process had begun there was a complaint through the telephone lines that the tenant in question had just stood up in their bathroom, when the toilet had erupted in a geyser that went everywhere.

This was from the same construction company that attempted to fill in a deep hole in the River Thames with liquid cement, only to find that they had filled in someone's basement / underground car park.