Oh, I just realized that more contact between the droplet and the larger body of water would through attraction probably lead to coalescence. The vibration probably keeps the droplet and water surface from making enough contact for long enough time to join together. Again, I need to know more about the underlying physics.

I can imagine that a flat surface meeting the curve of the droplet makes for a smaller surface area of contact than if the convex curve of the droplet meets a concave curve of the vibrating water. Maybe the weight of the droplet ensures that it will always be in a concave part of the vibrating surface. I don't know enough about surface tension at an atomic level to really have any good ideas on this.

Basic points paraphrased from the article:

There are two speakers facing each other which are both producing the same tone. They are adjusted so that the waves interfere perfectly with each other, creating what's called a "standing wave". At the places where both waves have zero volume, called "nodes", the pressure coming up from the one wave and pressure coming down from the other is exactly equal, and they are strong enough to counteract gravity, so very light things can be suspended in mid air.

In this video, the guy adjusts the wave-o-metre thingie up and down, and it moves the nodes up and down, and the droplets move up and down as well.

>> ^mizila:

>> ^jimnms:
If they coated boat hulls with this stuff, would they cut through the water more efficiently?

No, that's how you make hovercrafts. :-P
But seriously, smooth hulls are actually bad for speed. Ideally you want little pockets of air to make a good boundary for the laminar flow of water going past. Some people even sand the hulls of their racing boats. Think about the dimples on a golf ball, same idea. Although it'd be an awesome product for the windshield of a boat. =)


Yep good point, and if you look at/touch shark skin, it's essentially sand paper; helps them move faster through water apparently.

>> ^jimnms:

If they coated boat hulls with this stuff, would they cut through the water more efficiently?


No, that's how you make hovercrafts. :-P

But seriously, smooth hulls are actually bad for speed. Ideally you want little pockets of air to make a good boundary for the laminar flow of water going past. Some people even sand the hulls of their racing boats. Think about the dimples on a golf ball, same idea. Although it'd be an awesome product for the windshield of a boat. =)

Or get a strobe light with adjustable flash rate. Then you can see this effect in real time.

I spent one evening with a bunch of friends, a strobe light and a dark, indoor swimming pool. Lotsa trippy fun. >> ^Zawash:

Brilliant - got to try this at home. Hmm - by slowly increasing the shutter speed, the water should go from flowing water to still droplets like in the video. A simple 25Hz wave should be great for recording at 25fps.

Brilliant - got to try this at home. Hmm - by slowly increasing the shutter speed, the water should go from flowing water to still droplets like in the video. A simple 25Hz wave should be great for recording at 25fps.

Your video, water droplets orbiting a seweing needle, has made it into the Top 15 New Videos listing. Congratulations on your achievement. For your contribution you have been awarded 1 Power Point.

Tags for this video have been changed from 'space, low gravity, water droplets, static charge, nasa, iss' to 'space, low gravity, water droplets, static charge, nasa, iss, knitting needle' - edited by xxovercastxx

Thanks.

In reply to this comment by Lann:
Tada! I think it was the one from r/pics but might as well upboat the oldest.

Tada! I think it was the one from r/pics but might as well upboat the oldest.

>> ^charliem:

Hot oil + water = Fire.
That would be a bad idea
Leidenfrost works on the principle of the evaporation point of a fluid on a super hot surface creating a 'steam' (read: gas) interface between the surface and the fluid, for the fluid to float on free of surface tension forces...creating the droplets you see dancing on a hot skillet.
Seeing as oil has no evaporation point, and hot oil and water mix to create fire (the oil is aerosolized by the rapid turning of water to steam, causing it to explode when it gets enough air/fuel mix), I dare say he has dry hands to begin with.
Hes just a freak.
>> ^smooman:
>> ^charliem:
>> ^smooman:
looks like the leidonfrost effect me thinks?

Unlikely. Leidonfrost is the other way around, cold liquids on super hot surfaces.
Besides, oil doesnt have an evaporation point, it has a flashpoint....leidonfrost certainly doesnt apply here.

it would work if his hands were wet? i thought that was a principle of leidenfrost?
if not then one of three things is happening:
1) he has hyper resilient skin in which case he must be studied by science STAT
2) he's a witch in which case BURN HIM
3) jesus, in which case, repent



ya forgot about water and hot oil making fire.

Hot oil + water = Fire.
That would be a bad idea

Leidenfrost works on the principle of the evaporation point of a fluid on a super hot surface creating a 'steam' (read: gas) interface between the surface and the fluid, for the fluid to float on free of surface tension forces...creating the droplets you see dancing on a hot skillet.

Seeing as oil has no evaporation point, and hot oil and water mix to create fire (the oil is aerosolized by the rapid turning of water to steam, causing it to explode when it gets enough air/fuel mix), I dare say he has dry hands to begin with.

Hes just a freak.

>> ^smooman:

>> ^charliem:
>> ^smooman:
looks like the leidonfrost effect me thinks?

Unlikely. Leidonfrost is the other way around, cold liquids on super hot surfaces.
Besides, oil doesnt have an evaporation point, it has a flashpoint....leidonfrost certainly doesnt apply here.

it would work if his hands were wet? i thought that was a principle of leidenfrost?
if not then one of three things is happening:
1) he has hyper resilient skin in which case he must be studied by science STAT
2) he's a witch in which case BURN HIM
3) jesus, in which case, repent