Stories
Slash Boxes
Comments

SoylentNews is people

posted by martyb on Monday September 03 2018, @09:41AM   Printer-friendly
from the Lawrence-Welk dept.

Ars Technica:

A team of mathematicians has devised the most precise recipe yet for blowing perfect bubbles, and it's not just for fun and frolics. Achieving a better understanding of the dynamics at work could lead to more efficient industrial production of commercial sprays and foams, like shaving cream or Reddi-Wip—pretty much anything that has drops or bubbles in it.

[...] Just two years ago, French physicists worked out a theoretical model for the exact mechanism for how soap bubbles form when jets of air hit a soapy film. They tested their model by hanging weighted fishing line from a three-foot contraption. Then they carefully dripped a soapy solution (a bit of Dawn dish soap in plain tap water) onto the top of the wires so the wires stuck together as it dribbled down. Gently pulling the wires apart again created a thin soap film. Then they zapped the film with jets of gas to see which speeds of blowing air produced bubbles, filming it all with a high-speed camera.

"We can now say exactly what wind speed is needed to push out the film and cause it to form a bubble."

The results: bubbles only formed above a certain speed, which in turn depends on the width of the jet of air. If the jet is wide, there will be a lower threshold for forming bubbles, and those bubbles will be larger than the bubbles produced by narrower jets with their higher speed thresholds. The former is often the case when we blow bubbles through a little plastic wand: the jet forms at our lips, and is usually wider than the soapy film suspended within the wand.

In a new paper in Physical Review Letters, mathematicians at New York University's Applied Math Lab have fine-tuned the recipe for the perfect bubble even further based on similar experiments with soapy thin films. "We can now say exactly what wind speed is needed to push out the film and cause it to form a bubble, and how this speed depends on parameters like the size of the wand," said co-author Leif Ristroph. The answer: you want a circular wand with a 1.5-inch perimeter, and you should gently blow at a consistent 6.9 cm/s. Blow at higher speeds and the bubble will burst. Use a smaller or larger wand, and the same thing will happen, or the bubbles will be smaller, or perhaps not form at all.

[...] DOI: Physical Review Letters, 2018. 10.1103/PhysRevLett.121.094501  (About DOIs).


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 0) by Anonymous Coward on Monday September 03 2018, @01:24PM (3 children)

    by Anonymous Coward on Monday September 03 2018, @01:24PM (#729836)

    Don Ho

  • (Score: 0) by Anonymous Coward on Monday September 03 2018, @06:05PM (1 child)

    by Anonymous Coward on Monday September 03 2018, @06:05PM (#729918)
    • (Score: 0) by Anonymous Coward on Monday September 03 2018, @06:14PM

      by Anonymous Coward on Monday September 03 2018, @06:14PM (#729923)

      Wow! That's really a great video! I had no idea that Ho did such an involved "call and response" at live performances. Thanks!

  • (Score: 0) by Anonymous Coward on Monday September 03 2018, @06:22PM

    by Anonymous Coward on Monday September 03 2018, @06:22PM (#729924)

    Nice reference!

    The reference to Lawrence Welk in the header is just as clever:
    "... and now-a, Bobby and-a Cissy will-a perform a wunnerful dance to the 'Pennsylvania Polka!'"