My understanding of it after a quick read of the paper: you want to make a suction cup. The usual way is with a solid cup (think plastic) with a softer rubber-like ring around it. Near the ring, you will have atmospheric pressure (high) outside, and vacuum pressure (low) inside, so if the ring doesn't make perfect contact with the surface, some air is going to come in and ruin you vacuum. What they are doing is that they are rotating a bit of water in the suction cup, which because of centrifugal force will come close to the suction cup frontier in a ring-like shape. This water ring will -- thanks to fluid mechanics black magic -- have a different pressure at its exterior and its interior. Its interior pressure will necessarily be the same as the vacuum, and you can make it so that the pressure outside is the same as the atmospheric pressure, hence, according to this paper, if the rubber ring fails to make hermetic contact, air won't come in because at the frontier of the cup, the pressure is the same both outside (atmosphere) and inside (exterior of the water ring).
New suction-cup system spins water to stick to rough surfaces
21–30 of 35 posts
Re: New suction-cup system spins water to stick to rough surfaces
#22Pretty 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.
This has many of the red flags for "technological" development that won't withstand scientific scrutiny.
What flags, specifically?
Re: New suction-cup system spins water to stick to rough surfaces
#23Re: New suction-cup system spins water to stick to rough surfaces
#24I can't say I am super looking forward to hexapod wall climbing robots.
Re: New suction-cup system spins water to stick to rough surfaces
#25Earlier quoted context omitted.
The videos are great, consumes a lot less water than I imagined. Seems like most of the water is lost during the de-suction process, if they can scavenge that it could really cut the water consumption down nearly to zero.
If they have an additional ring around the outside of each cup, could they not suction the water back into the system? Also, wouldnt this be easily defeatable with small dowel protruding "thorns" - or dimples, as on a golf ball - maybe alternating convex/concave dimple patterns? or other ridges?
I don’t think it’s possible to build a suction cup (or in fact any climbing tool) which will work 100% of the time against any countermeasure. However this design does seem a significant step forward from existing suction cups.
Re: New suction-cup system spins water to stick to rough surfaces
#26My understanding of it after a quick read of the paper: you want to make a suction cup. The usual way is with a solid cup (think plastic) with a softer rubber-like ring around it. Near the ring, you will have atmospheric pressure (high) outside, and vacuum pressure (low) inside, so if the ring doesn't make perfect contact with the surface, some air is going to come in and ruin you vacuum. What they are doing is that…
Does the water on the innermost edge of the rotating ring, which is exposed to the vacuum, NOT vaporize because the absolute pressure is still above 10kPa (100kPa atmospheric - 80kPa vacuum)? [0]
Will the seal slowly evaporate away or absorb into a porous surface like concrete?
[0] https://en.m.wikipedia.org/wiki/File:Phase_diagram_of_water....
Re: New suction-cup system spins water to stick to rough surfaces
#27Pretty 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.
This has many of the red flags for "technological" development that won't withstand scientific scrutiny.
Have to agree, he sounds a lot like those "infinite energy" guys that were around a few years ago.
Re: New suction-cup system spins water to stick to rough surfaces
#28What about ferromagnetic fluid? You can still spin it if you are aiming to push it 'centrifugally' into the features of the vacuum boundary, but you shouldn't lose a lot during the detachment. (Plus it looks much more sci-fi.)
Arduino controlled real live squid with water backpack. That’s the future.
I wonder if some sort of jelly would work to do the same thing, like a snail. Or a dynamic cup surface that conforms to the wall better.
Re: New suction-cup system spins water to stick to rough surfaces
#29Earlier quoted context omitted.
This has many of the red flags for "technological" development that won't withstand scientific scrutiny.
Have to agree, he sounds a lot like those "infinite energy" guys that were around a few years ago.
Pretty much anyone over 40 doing a home video in their garage is going to come across like that. It's really unfortunate, but appearances do matter, a lot.
In this case, besides the appearances, what the guy is demonstrating in the videos seems legit.
Here's an earlier video where he explains what he believes is the effect at work, with a simple demonstration: https://youtu.be/I3g0CcLzC6I
It would be awesome if a youtuber like Steve Mould or Dustin from SmarterEveryDay did a video on this.
Re: New suction-cup system spins water to stick to rough surfaces
#30actual paper https://aip.scitation.org/doi/10.1063/1.5129958 video 1 (response measurement): https://aip.scitation.org/doi/suppl/10.1063/1.5129958/suppl_... video 2 (picking up block): https://aip.scitation.org/doi/suppl/10.1063/1.5129958/suppl_... video 3 (hexapod): https://aip.scitation.org/doi/suppl/10.1063/1.5129958/suppl_... video 4 (human climbing tiled wall): https://aip.scitation.org/doi/suppl/10.1063/1.51299…
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.