Boffins don't want to burst your bubble – they create them with sound

Nerd out over bizarre ultrasonic fluid dynamics

Video Fluid dynamics is weird. Physicists have reverse engineered the popping of a bubble and managed to keep it levitated just by using the power of sound.

Iridescent bubbles form when a film of soapy liquid is punctured. The film retracts from the hole and the molecules are pulled back and rearranged to reduce its surface area, forming bubbles that eventually pop and shatter into tiny droplets.

A team of physicists decided to study the process in reverse. Starting with liquid droplets, they can be manipulated to grow bubbles. Acoustic levitation is often used in fluid dynamics to suspend and control bubbles in the air using sound waves. The results were published in Nature Communications on Tuesday.

You can watch the experiment below.

Youtube Video

Ultrasonic sound waves at highly energetic frequencies beyond the range of human hearing are emitted and reflected in between two plates. The pressure created from the waves keeps the bubble contained mid-air.

When the acoustic radiational force is applied to droplets, it stretches them into a thin film. As more pressure is applied, the film begins to buckle and grow into a bowl shape.

The volume of the bowl continues to grow and when it reaches a critical point, the air molecules trapped inside it begin vibrating at the same frequency as the sound waves to create a resonant cavity. Suddenly, the volume of the film inflates rapidly to form a spherical bubble.


Different stages of bubble formation. Image credit: Zang et al. and Nature Communications.

The acoustically levitating bubbles can stay suspended and last over tens of minutes without popping. Eventually, the bubbles do burst into droplets as the liquid begins evaporating. The researchers believe that studying the bubble formation process in detail will help the storage of food, cosmetics, or pharmaceuticals. ®

Similar topics

Broader topics

Narrower topics

Other stories you might like

  • AMD claims its GPUs beat Nvidia on performance per dollar
    * Terms, conditions, hardware specs and software may vary – a lot

    As a slowdown in PC sales brings down prices for graphics cards, AMD is hoping to win over the market's remaining buyers with a bold, new claim that its latest Radeon cards provide better performance for the dollar than Nvidia's most recent GeForce cards.

    In an image tweeted Monday by AMD's top gaming executive, the chip designer claims its lineup of Radeon RX 6000 cards provide better performance per dollar than competing ones from Nvidia, with all but two of the ten cards listed offering advantages in the double-digit percentages. AMD also claims to provide better performance for the power required by each card in all but two of the cards.

    Continue reading
  • Google opens the pod doors on Bay View campus
    A futuristic design won't make people want to come back – just ask Apple

    After nearly a decade of planning and five years of construction, Google is cutting the ribbon on its Bay View campus, the first that Google itself designed.

    The Bay View campus in Mountain View – slated to open this week – consists of two office buildings (one of which, Charleston East, is still under construction), 20 acres of open space, a 1,000-person event center and 240 short-term accommodations for Google employees. The search giant said the buildings at Bay View total 1.1 million square feet. For reference, that's less than half the size of Apple's spaceship. 

    The roofs on the two main buildings, which look like pavilions roofed in sails, were designed that way for a purpose: They're a network of 90,000 scale-like solar panels nicknamed "dragonscales" for their layout and shimmer. By scaling the tiles, Google said the design minimises damage from wind, rain and snow, and the sloped pavilion-like roof improves solar capture by adding additional curves in the roof. 

    Continue reading
  • Pentester pops open Tesla Model 3 using low-cost Bluetooth module
    Anything that uses proximity-based BLE is vulnerable, claim researchers

    Tesla Model 3 and Y owners, beware: the passive entry feature on your vehicle could potentially be hoodwinked by a relay attack, leading to the theft of the flash motor.

    Discovered and demonstrated by researchers at NCC Group, the technique involves relaying the Bluetooth Low Energy (BLE) signals from a smartphone that has been paired with a Tesla back to the vehicle. Far from simply unlocking the door, this hack lets a miscreant start the car and drive away, too.

    Essentially, what happens is this: the paired smartphone should be physically close by the Tesla to unlock it. NCC's technique involves one gadget near the paired phone, and another gadget near the car. The phone-side gadget relays signals from the phone to the car-side gadget, which forwards them to the vehicle to unlock and start it. This shouldn't normally happen because the phone and car are so far apart. The car has a defense mechanism – based on measuring transmission latency to detect that a paired device is too far away – that ideally prevents relayed signals from working, though this can be defeated by simply cutting the latency of the relay process.

    Continue reading

Biting the hand that feeds IT © 1998–2022