Bang But No Splash 252
BishopBerkeley writes "When a drop of ethanol is dropped on a surface at low pressures (1/5 atmosphere or less), it makes no splash. Science offers a brief synopsis and fascinating pictures of the phenomenon. The results seem to confirm the (perhaps counterintuitive) prediction that more viscous liquids are more likely to splash, not less likely . Links to the researchers' home page at U of Chicago (as of now, the site is timing out) and pdf version of the article on arxiv can be found on the Science page also."
We know quarks, but not this... (Score:5, Insightful)
Makes one wonder what else the laws of physics are hiding from us yet... and whether we have really tried to analyse physics systematically enough.
Re:We know quarks, but not this... (Score:5, Insightful)
To test this it seems like you could perform the experiment at higher temperatures. The hypothesis would be that the higher temps overcome the molecular interactions and decrease the viscosity.
I just looked at the pictures and am a biochemist so take this analysis, like everything else on
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Daniel Coughlin's Photographs [pbase.com]
Re:We know quarks, but not this... (Score:5, Insightful)
Re:Nice! (Score:2, Insightful)
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a very interesting question... (Score:3, Insightful)
important puzzle: why do we see a corona form at all? At the substrate surface the liquid momentum points horizontally outward. Without a layer of fluid to push against (such as in the photographs of Edgerton), how does the expanding layer gain any momentum component in the vertical direction?
That is an interesting question...sounds like a potential thesis for a few people out there.
Comment removed (Score:4, Insightful)
As Dave Barry pointed out.... (Score:5, Insightful)
looking at the pix (Score:4, Insightful)
Re:An accessible page, more types of fluids tested (Score:3, Insightful)
Real world.. (Score:3, Insightful)
Re:Air pressure is critical (Score:5, Insightful)
How about a partially elastic collision with the surface (it bounces)?
How about collision with the leading edge of the spreading droplet (there is drag on the spreading drop as it extends across the surface--fast liquid building up behind could still splash over that barrier, even in the complete absence of atmosphere)?
Always be afraid of "intuitive" reasoning in physics when you're dealing with very slow or very fast processes that operate on very small or very large scales. :)
Re:Real world.. (Score:5, Insightful)
Some examples..Transistors arose from some guys shooting the breeze 20-30 years earlier as to how electrons moved around. What they were saying made no sense at all but it paid off big time. A guy sitting in a patent office speculates that light is comprised of particles and uses it to explain why electrons stream out of certain metals. Same guy speculates about what it's like to sit on a photon as it screams along and draws a few conclusions that 35 years later, rock the world. Another guy grows 1000s of peas, counts, by hand, how many of eight different traits show up in subsequent generations and figures out that wrinkled peas require wrinkled parents. Thirty years later, some other guys pick up on that idea and study fruit flys and come up with an arithmetic argument based on percentages that some traits are based on discrete loci. Weird stuff in 1911 that blossomed into billion dollar corporations 70 years later. A pair of mathematically gifted brothers figure out some equations about how fluids move over surfaces. That knowledge sits around for more than a 100 years before a different pair of brothers in a bike shop put the knowledge to an interesting use.
You just never know what's worth knowing so we gather what we can.
Re:We know quarks, but not this... (Score:3, Insightful)
This sounds like something that could be easily explained. When you blow into a balloon, the air inside does not stretch the latex evenly in all directions. By evenly, I mean that the latex is thicker and thinner in some areas than others due to imperfections in manufacturing. When you blow up the balloon, these imperfections aren't accounted for and there are likely to be a few "weakest" areas with some stronger ones around.
In theory, removing the surrounding air would eliminate or significantly reduce the opposition to this "uneven" (when considering the imperfect makeup of the balloon itself) distribution, and allow the air inside the balloon to distribute itself so that all points on the balloon's surface experience the same tension to strength ratio. Once a certain threshold is exceeded, they would then all exceed it at the same time, and result in many many tears, opposed to just a few.
Re:Real world.. (Score:2, Insightful)
Re:Bad link (Score:3, Insightful)
Bah! Subtle my eye! It's trivial to run your links through an anonymizer to ensure full public access is allowed. Of course, doing this would constitute effort, and it's abundantly clear that /. editors avoid that at all cost...
Re:We know quarks, but not this... (Score:4, Insightful)
The pressure differential between the inside of the balloon and the outside is probably identical in both cases when the balloon pops. So the net force acting on the surface of the ballon at the moment of the pop should be the same. The only difference is the absolute pressure. I think this is the key.
The pressure in the jar is so low that when the balloon breaks, there is no force pushing inward on the ballon. The net force is basically equal to the force pushing outward. At regular atmospheric pressure there is more force on the inside but also resistance from the outside. I think the outside pressure affects the rubber after the instant of the pop by slowing it down. Maybe this keeps the rubber stable enough to only break into a few pieces.