Live data from Hacker News

New suction-cup system spins water to stick to rough surfaces

newatlas.com

31–35 of 35 posts

Re: New suction-cup system spins water to stick to rough surfaces

#31
> The resulting inertial force generates a steep pressure gradient, allowing a high vacuum to be maintained at the center of the cup's vacuum zone

Sounds like a "momentum transfer" vacuum pump, shaped so that the output side bleeds out along the rim.

https://en.wikipedia.org/wiki/Vacuum_pump#Momentum_transfer_...

Re: New suction-cup system spins water to stick to rough surfaces

#32

Pretty cool. Reminded me of what this guy is doing, he calls it "orthosonic lift": https://youtu.be/kG6vXGidQbo Some more info: http://sciencechatforum.com/viewtopic.php?nomobile=1&f=77&t=... I believe he has a couple of patents on the technology, but not sure he'll ever get around to making something practical with it.

Just wanted to throw my opinion into the mix.

I watched multiple of the videos he has listed and from what I can tell the phenomenon he is demonstrating is real and reproducible.

Whether or not he's crazy, who's to say?

Re: New suction-cup system spins water to stick to rough surfaces

#33
post #19
post #5

Earlier quoted context omitted.

No, I believe the immersion blender trick can be explained by https://en.wikipedia.org/wiki/Bernoulli%27s_principle Whereas the suction cups in the article, use spinning water as a way to seal suction cups on rough surfaces (the water fills in crevices of rough surfaces I presume, allowing the suction cup to seal). The water is also spinning (i.e. it has an inertial force) so that it counteracts the vacuum pressure i…

Hmmm. At a glance I can’t figure out how Bernoulli’s law applies. The blender trick looks very similar to the original article to me. Could anybody explain in more detail?

Well for one, the linked video example of the Styrofoam plates and hair dryer (shown right before the immersion blender) is definitely due to Bernoulli's law. See https://en.wikipedia.org/wiki/Bernoulli_grip

As for the immersion blender, intuition should tell you that the same principle should/or at the very least… might apply. Now it could very well not apply (but I'm quite confident that it does). To really prove if it does or not, one would have to do the rigorous math involved, which would include deriving the stream function for the flow situation, verifying if conditions allow for applying Bernoulli's principle, then applying the principle and verifying if it matches experimental observations... This is would be non-trivial to do (judging simply by the geometries involved) so I'm not even going to attempt do this…

However, I’ll try explaining the gist of the idea:

Bernoulli’s principle basically states that, within a flow of constant energy, when a fluid speeds up, it is corresponded with a drop in pressure and vice versa. Now looking at the immersion blender, intuition (and essentially conservation of mass) suggests that the fluid should be moving fastest between the edges of the blender/blade and the boundaries of the container/cup (i.e. areas where there’s very little space near the moving blender parts). Outside these regions, intuition would suggest the fluid is moving relatively slowly (e.g. near the top of the water level in the container cup). Since the fluid appears to move, and likely cross these regions (i.e. undergoes speeding up/slowing down), Bernoulli’s principle states that we should expect to see a pressure differential between these regions, where faster moving water regions should be at a lower pressure (i.e. acting as a vacuum / suction cup).

But again, whether or not this idea is true and is valid would have to be mathematically and experimentally verified…

Re: New suction-cup system spins water to stick to rough surfaces

#34

Earlier quoted context omitted.

This is very interesting. I wonder how the power use compares with achieving a similar effect using a vacuum pump.

Edit: I got downvoted. Is a powered vacuum pump not possible in this application? (Like putting a vacuum cleaner nozzle against the wall, possibly using a more powerful motor than usual, for more suction.) I think it's a fair question but maybe I'm way off base here.

Presumably you were downvoted because your question suggests that you haven't actually read the article, which does mention how it compares to other powered suction (i.e. "vacuum pump") devices.

Re: New suction-cup system spins water to stick to rough surfaces

#35
post #14

Pretty cool. Reminded me of what this guy is doing, he calls it "orthosonic lift": https://youtu.be/kG6vXGidQbo Some more info: http://sciencechatforum.com/viewtopic.php?nomobile=1&f=77&t=... I believe he has a couple of patents on the technology, but not sure he'll ever get around to making something practical with it.

The patent won’t hold. We have prior art from alien spacecraft for decades now. Most of our current propulsion and lift mechanisms are based on momentum transfer, which has many problems in air. His work makes me think there are a lot more efficient mechanisms to be discovered.

okay; sorry. I was trying to compliment him on something I found interesting by alluding to it being alien technology. I took aeronautical engineering a long time ago, and I've never seen anything like this, so maybe it's just a foolish amazement.
Post reply on HN