I found his write-up on MBTA bus mirror positioning to be a short but interesting read as well: https://alexanderellis.github.io/blog/posts/mbta-bus/
Why does a spray bottle work?
21–30 of 132 posts
Re: Why does a spray bottle work?
#22This is a nice example to show the illusion of explanatory depth [0]. Most people would say they know how a spray bottle works, but fail to describe all relevant details of the implementation, [0] https://www.edge.org/response-detail/27117
There is a relevant interview [0] with Feynman that I always remember.
[0] https://www.lesswrong.com/posts/W9rJv26sxs4g2B9bL/transcript...
Re: Why does a spray bottle work?
#23I found his write-up on MBTA bus mirror positioning to be a short but interesting read as well: https://alexanderellis.github.io/blog/posts/mbta-bus/
Many of the buses I've seen in parts of southeast Asia have their side mirrors hanging in the front instead of jutting out the side, probably for a similar reason (and the streets there are much narrower too.)
Re: Why does a spray bottle work?
#24How does the nozzle diffuse?
Fluid dynamicist here who works on the breakup of larger water jets. How the jet breaks up depends on the design of the system. (I assume you mean break up, not diffuse. Diffusion is a different physical process which occurs independent of breakup.)
A low speeds (laminar flow), Rayleigh's analysis shows that a simple liquid jet breaks up due to surface tension effects.
https://en.wikipedia.org/wiki/Plateau%E2%80%93Rayleigh_insta...
At higher speeds (e.g., transitional or turbulent flows), the mechanisms change. For your typical spray bottle (without a swirl chamber) I'd say turbulence is the primary cause of breakup. Aerodynamic influence won't factor in at typical air densities and cavitation isn't happening as it probably would break the nozzle.
Here's a conference paper I wrote on turbulent breakup theory, which hopefully is readable for anyone with an understanding of probability theory and basic turbulence theory: https://engrxiv.org/35u7g/
(RMS velocity is just the standard deviation of the velocity. Turbulent kinetic energy is an energy formed from the RMS velocity. Kolmogorov's 5/3 theory is used a bit, but you can just view it as power law distribution. Etc.)
I also have some small spray bottles with swirl chambers, which makes the bulk fluid spin, destabilizing the interface, leading to droplet formation. The spray angle for these is large compared against the simple pressure atomizer described previously.
Re: Why does a spray bottle work?
#25A very simple design, based on a principle that was discovered over 2000 years ago. http://www.mdpi.com/2073-4441/7/9/5031/pdf (see page 13-14) https://en.wikipedia.org/wiki/Piston_pump
That diagram at the top of the Wikipedia article made the concept more clear to me than the whole orginal post. Drawing the valves like that really helps.
Edit: grammar
Re: Why does a spray bottle work?
#26One way valves are basically diodes, but for fluids rather than electrons. You can also make logic gates out of just diodes (or one way valves). Imagine writing software for a hydraulic computer!
> One way valves are basically diodes, but for fluids rather than electrons.
The analog of the fluid in that analogy is electric charge/current, not electrons which move in the other direction (which kinda breaks the analogy as a result).
Re: Why does a spray bottle work?
#27One way valves are basically diodes, but for fluids rather than electrons. You can also make logic gates out of just diodes (or one way valves). Imagine writing software for a hydraulic computer!
MONIAC [1] was an analog computer designed in 1949 that used water to model the national economy of the United Kingdom.
Re: Why does a spray bottle work?
#28A few years ago, a British inventor appeared on a TV show called Dragon's Den (UK version of Shark Tank) and pitched his idea of an improved spray bottle called the Anyway Spray.
Instead of a normal plastic tube inside a bottle with an opening at the end, he designed a tube with millions of tiny perforations along its length. This meant the spray bottle could operate at any angle (even upside down) and could empty all liquid in a bottle with no leftover.
Here is a 1 min demo of the spray: https://vimeo.com/195318537
Here's an explanation of how it works https://www.youtube.com/watch?v=xXk46rvzdpY
And here's the original pitch he made on Dragon's Den https://www.youtube.com/watch?v=RjOvyjeZyIw
Re: Why does a spray bottle work?
#29Having source be in the "staging area" after "git add" makes more sense to me now :-)
I think this use of "staging area" comes from the military use, which in turn comes from the theater "staging", both predating git and the bottle.
Re: Why does a spray bottle work?
#30I would have loved this explained in my high school physics class