HERE'S a Zen-like question. If a drop of liquid falls on a flat surface and there is no air around it, does it make a splash?
The answer, which may or may not help you reach nirvana, is no. "This was to us an incredibly surprising result," says Sidney Nagel of the University of Chicago in Illinois. "If you didn't have the air, you couldn't splash. This means you would never get splashing on the moon."
Nagel and fellow physicists Lei Xu and Wendy Zhang were trying to measure the energy of liquid droplets flying away from splashing drops of alcohol. To eliminate any effects of air, they carried out the experiment in a vacuum chamber, where they could reduce the pressure within the chamber from the standard atmospheric pressure of about 1 bar down to 10 millibars. The team found that the lower the air pressure, the less the liquid splattered. And the splash disappeared when the air pressure reached about 0.2 bar.
Of course it is.Integral said:Come on Russ, think for a second, do you really believe that meteor impact on the surface of a planet is analogous to droplet formation in a fluid?
Really? what is the surface tension of a planet?DaveC426913 said:Of course it is.
I am curious as to what did happen in the experiment. The article seems to regard that as inconsequential.
Ref: http://www-news.uchicago.edu/releases/05/050322.splash.shtmlUniversity of Chicago physicists have learned how to eliminate what scientists formerly regarded as the inevitable splashing that occurs after a liquid crashes onto a flat surface. It turns out that the removal of air eliminates the splash process. ...
Xu’s path to discovery began with an experiment designed to study energy distribution in the many pieces that fly away from a breaking droplet. The experiment showed that after a droplet hits a flat, dry surface, it forms a thin layer that breaks into thousands of pieces. Xu then repeated the experiment in a vacuum chamber and lowered the air pressure. He and Nagel figured that the drag of the surrounding air might play some role in the break-up process.
“Once we lowered the pressure and did the experiment, it didn’t have any splash,” Xu said. ...
Researchers in the field previously had seen no reason for low atmospheric pressure to affect the results of their splash experiments. “There are many people working on this because it’s a very important technological area,” Zhang said. “Up until Lei’s experiment, the idea in the field of splashing is that of course the air doesn’t do anything, because it’s less dense and less viscous than water,” she said.
Instead, splash researchers generally focused on the interaction between the spreading droplet and the surface against which it collided. Their carefully controlled experiments produced reams of data but little understanding of the fundamental mechanism for splash formation.
“One of the things that is notorious in the splash-study community is that it’s very difficult to reproduce somebody else’s experiment. People have been working on this for more than a hundred years, and it is only recently that we understand enough about the different factors that affect the splash process to be able to reproduce results,” Zhang said.
The Chicago physicists isolated the effects of air pressure on splashing through a painstaking series of experiments involving four different gases and three different liquids. The gases selected—helium, air, krypton and sulfur hexafluoride—ranged from light to heavy. The fluids—methanol, ethanol and 2-propanol—have low surface tension, the force that makes a layer of liquid want to retract and form a droplet.
Xu tested water splash as well. Water exhibits the same behavior, but its higher surface tension narrows the range of splash-forming impact velocity and creates a much larger margin for experimental error.
“It’s much harder to splash than ethanol,” he said.
Xu found that he could precisely control the amount of splash by tuning the pressure. The next step, he said, might be to investigate splash outcomes under experimental scenarios involving very large or very small drops, or drops traveling at higher velocities.
Integral said:Really? what is the surface tension of a planet?
It would look like a room full of vapour. You won't have liquid water in a vacuum for very long...GOD__AM said:I wonder what dropping a cannon ball into a pool of water with no air would look like. Would we see some splashing then?
Water does not splash in a vacuum because there is no medium for it to displace and create a wave. In order for a liquid to splash, it needs to come into contact with another surface or air, which is not present in a vacuum.
No, water cannot splash in a vacuum on Earth. Even if a vacuum is created in a controlled environment on Earth, there will still be air particles present which will prevent the water from splashing.
In a vacuum, water will evaporate quickly due to the lack of air pressure. The water molecules will spread out and be able to escape into the vacuum, turning into water vapor.
No, other liquids will also not splash in a vacuum for the same reason as water. Any liquid needs a medium to displace in order to create a splash.
Understanding why water won't splash in a vacuum is important for scientific research and space travel. It helps us understand the behavior of liquids in different environments and how they may behave in space, where vacuums are present. This knowledge can also be applied to improve technologies such as vacuum pumps and vacuum packaging.