3 ms·

Couple thoughts: The jitter is likely due to the suction pulling the air from the outside of the tubes, which then get pulled in the gap between the things - w

Couple thoughts: The jitter is likely due to the suction pulling the air from the outside of the tubes, which then get pulled in the gap between the things - which does so in a buffeting fashion due to the movement of the pipes, so it finds the oscillation... (the tubes are a Foil - so you have to accomodate the flow diff on the external and internal of your receiving tube - and how the flows from the outside of the foil are a diff speed/flow/rate than the center of the tube - thus the light suction guy gets enough strength for the outside air to push it back - once it gets far enough from the horizontal tube, the pressure from the outside flow drops and the lever goes back to its resting position and begins again) The other thing, as he mentioned eddys -- the inlet and outlet cones should be turbine-spiral shapes - as the air/fluid comes down the pipe, if you give it a spiraling/riffling it will keep the flow somewhat cohesive as it spins it. Further, as a YT comment mentioned - stuffing a bunch of small straws in the main tube helps, because if you have a lot of smaller tubes - (especially with water) you can get the effective "orientation of the molocules" the same - so your stream can be more cohesive (this method was (invented?employed) by Disney Land Engineers when they were building the fountains that shoot clean, cohesive lasers of water. They run the streams to the fountain through pipes that have a ton of staws inside - so the water gets orientated in such a way that when the stream leaves the nozzle, the water stays together. Also - you can test all this in FluidX3d: https://github.com/ProjectPhysX/FluidX3D https://github.com/ProjectPhysX/FluidX3D -- The Eddy Pump was first invented by Leo Davinci... and now we have great pumps like: https://eddypump.com/pump-videos https://eddypump.com/pump-videos -- The eddy is the most important thing to understand in fluid dynamics IMO. (its what your Heart is, BTW) ---- @Btrettel: THANKS! I couldn't think of the term laminar... And I was simplifying "stuffing straws".. Appreciate the input. Have you tried FluidX3D?

btrettel 3y ago
> stuffing a bunch of small straws in the main tube helps, because if you have a lot of smaller tubes - (especially with water) you can get the effective "orientation of the molocules" the same - so your stream can be more cohesive This is not the right way to think about it. The straws reduce turbulence by preventing fluid motion in a radial direction, and reduce swirl by preventing a swirling motion. (The screens have similar effects.) Both turbulence and swirl prevent the formation of a coherent liquid jet. The straws (and screens) aren't without disadvantages as they will cause significant pressure losses. How I know: I did a PhD on the range of large fire-fighting water jets and ended up reading a LOT of laminar fountain stuff online out of curiosity. > this method was (invented?employed) by Disney Land Engineers when they were building the fountains that shoot clean, cohesive lasers of water Definitely employed. Flow straighteners (or flow conditioners, or whatever you want to call them) were quite common for turbulence and swirl reduction in general before laminar fountains appeared. I recall seeing patents with flow straighteners for fire-fighting purposes in the 1930s, and I'm confident that they were in use in other areas earlier than that. *** A side note: Laminar fountains are neat, but you'll find a ton of misinformation about how they work online. I started writing more, but Brandolini's law comes into play, and I don't have the time to go into it.
dreamcompiler 3y ago
> its what your Heart is, BTW There are certainly eddy currents within the heart, but the heart is not an eddy pump. As pumps go, the heart is most similar to a reciprocating volumetric pump.
- samstave 3y ago
  I should have said "Eddies are fundamental to how the heart works" ;-)
  - NoZebra120vClip 3y ago
    Eddies in the space-time continuum?
    - chrisrd 3y ago
      Is he?
btrettel 3y ago
> Appreciate the input. Have you tried FluidX3D? Glad to help. I'm not familiar with FluidX3D. Lattice Boltzmann methods are uncommon, probably because they are computationally expensive. I'm a finite volume and finite difference guy myself. Finite volume methods are the most common approach in computational fluid dynamics.
- samstave 3y ago
  Do you recall they showed the blip that the google folk made, and it was in the hangar at Moffett field... they were showing all the different motors and sensors - and it was brought up that they had LIDAR sensors pointing at the interior helium balloon... and someone asked why they would be lidaring the thing... I surmised that they were using it to calculate the internal volume due to the deformation of the balloon as it loses volume.... was I correct? https://techcrunch.com/2023/11/08/the-worlds-largest-aircraft-breaks-cover-in-silicon-valley/ https://techcrunch.com/2023/11/08/the-worlds-largest-aircraf...
  - btrettel 3y ago
    Sorry, blimps aren't my area of expertise. I don't know what's going on there.
    - samstave 3y ago
      Its just a giant helium balloon inside the thing - https://youtu.be/FrAc-yORdAo?t=170 https://youtu.be/FrAc-yORdAo?t=170 - So its "finite" just not small.
mhb 3y ago
"After graduating from Stanford, Fuller worked as an Imagineer for The Walt Disney Company, applying the laminar flow technology he developed and refined to create Disney's “Leapfrog” fountain feature at Epcot Center." https://en.wikipedia.org/wiki/Mark_W._Fuller https://en.wikipedia.org/wiki/Mark_W._Fuller

btrettel 3y ago

> stuffing a bunch of small straws in the main tube helps, because if you have a lot of smaller tubes - (especially with water) you can get the effective "orientation of the molocules" the same - so your stream can be more cohesive This is not the right way to think about it. The straws reduce turbulence by preventing fluid motion in a radial direction, and reduce swirl by preventing a swirling motion. (The screens have similar effects.) Both turbulence and swirl prevent the formation of a coherent liquid jet. The straws (and screens) aren't without disadvantages as they will cause significant pressure losses. How I know: I did a PhD on the range of large fire-fighting water jets and ended up reading a LOT of laminar fountain stuff online out of curiosity. > this method was (invented?employed) by Disney Land Engineers when they were building the fountains that shoot clean, cohesive lasers of water Definitely employed. Flow straighteners (or flow conditioners, or whatever you want to call them) were quite common for turbulence and swirl reduction in general before laminar fountains appeared. I recall seeing patents with flow straighteners for fire-fighting purposes in the 1930s, and I'm confident that they were in use in other areas earlier than that. *** A side note: Laminar fountains are neat, but you'll find a ton of misinformation about how they work online. I started writing more, but Brandolini's law comes into play, and I don't have the time to go into it.

dreamcompiler 3y ago

> its what your Heart is, BTW There are certainly eddy currents within the heart, but the heart is not an eddy pump. As pumps go, the heart is most similar to a reciprocating volumetric pump.

samstave 3y ago
I should have said "Eddies are fundamental to how the heart works" ;-)
- NoZebra120vClip 3y ago
  Eddies in the space-time continuum?
  - chrisrd 3y ago
    Is he?

btrettel 3y ago

> Appreciate the input. Have you tried FluidX3D? Glad to help. I'm not familiar with FluidX3D. Lattice Boltzmann methods are uncommon, probably because they are computationally expensive. I'm a finite volume and finite difference guy myself. Finite volume methods are the most common approach in computational fluid dynamics.

samstave 3y ago
Do you recall they showed the blip that the google folk made, and it was in the hangar at Moffett field... they were showing all the different motors and sensors - and it was brought up that they had LIDAR sensors pointing at the interior helium balloon... and someone asked why they would be lidaring the thing... I surmised that they were using it to calculate the internal volume due to the deformation of the balloon as it loses volume.... was I correct? https://techcrunch.com/2023/11/08/the-worlds-largest-aircraft-breaks-cover-in-silicon-valley/ https://techcrunch.com/2023/11/08/the-worlds-largest-aircraf...
- btrettel 3y ago
  Sorry, blimps aren't my area of expertise. I don't know what's going on there.
  - samstave 3y ago
    Its just a giant helium balloon inside the thing - https://youtu.be/FrAc-yORdAo?t=170 https://youtu.be/FrAc-yORdAo?t=170 - So its "finite" just not small.

mhb 3y ago

"After graduating from Stanford, Fuller worked as an Imagineer for The Walt Disney Company, applying the laminar flow technology he developed and refined to create Disney's “Leapfrog” fountain feature at Epcot Center." https://en.wikipedia.org/wiki/Mark_W._Fuller https://en.wikipedia.org/wiki/Mark_W._Fuller