Skip to main content

The Matryoshka Effect: USU Researchers Describe Underwater Phenomenon

Wednesday, Apr. 25, 2018


Image of a unique underwater phenomenon that’s been likened to the Matryoshka doll

Researchers at USU's Splash Lab uncovered the physics behind a unique underwater phenomenon that’s been likened to the Matryoshka doll — the traditional Russian doll within a doll. (Chris Mabey)


Researchers at Utah State University are sending cascades of water into a tank to uncover a mystery of fluid dynamics. 

After a yearlong research study, the team of engineers and fluid dynamicists uncovered the physics behind a unique underwater phenomenon that’s been likened to the Matryoshka doll — the traditional Russian doll within a doll.

In a study published last week in the Journal of Fluid Mechanics, researchers from USU’s Splash Lab describe what happens when rapid-succession water droplets impact a calm surface and create a cavity of air beneath the water.

“When a stream of droplets hits the surface, it pulls air under and creates an air-filled cavity,” says lead author and PhD candidate Nathan Speirs. “The shapes of the cavities vary based on the impact parameters such as the diameter of the droplet and the speed at impact.”

When a continuous stream of water — a jet — impacts the water surface, it forms a cylindrical-shaped, deep, narrow cavity. When slow-succession droplets impact the water, they form individual cavities that close and collapse before the next droplet hits. The Splash Lab team wanted to know what happens when rapid-succession droplets impact the water. The result is a unique cavity made of a series of cavities within cavities that give the overall cavity a ribbed appearance.

“If the frequency of the falling droplets is high enough, the drops hit the same spot and create nested cavities,” said Speirs. “Each successive droplet forms a cavity at the base of the preceding cavity.”

Distinguishing the threshold between high and low frequency is a key part of the team’s findings. Speirs says there has never been a number that defines that threshold. So he and his team developed one.

“We can define the types of cavities based on a new dimensionless number we call the Matryoshka number. If the number is less than one, the cavity will collapse before the next droplet hits. If it’s above one, we predict to see the formation of nested cavities.”

The researchers say their study offers new applications to everyday life. 

“It has been known for a long time that a jet of fluid transitions into a stream of droplets just a few inches from the source of the jet,” said co-author and USU Associate Professor Tadd Truscott. “This means that when common daily jets impact a pool of water — such as water from a faucet into a kitchen sink or a stream of urine falling into a toilet — the droplet streams create cavities similar to those we’re studying at the Splash Lab.”

Understanding the nuances of splash types could lead to devices that reduce splash back and provide cleaner environments.

In industry, a more thorough understanding of this never-before-explained aspect of fluid dynamics could lead to advances in manufacturing chemicals and pharmaceuticals. Speirs says the findings are especially useful for developing safer and more efficient processes in which splash back is a concern.

Researcher Contact: Dr. Tadd Truscott – Dept. of Mechanical and Aerospace Engineering, Utah State University | tadd.truscott@gmail.com | office: +1-435-797-8246 | @TheSplashLab | splashlab.org
For additional media assistance, contact Matt Jensen – USU College of Engineering | matthew.jensen@usu.edu | office: +1-435-797-8170| cell: +1-801-362-0830 | @EngineeringUSU | engineering.usu.edu 





Post your Comment

We welcome your response. Your comment or question will be forwarded to the appropriate person. Please be sure to provide a valid email address so we can contact you, if needed. Your submission will NOT be published online. Thank you.

More News

All news


Subscribe

Utah State Today is available as a weekly e-mail update, with links to news, features, and events. Subscribers stay connected, whether on campus or off.

To receive Utah State Today every week, simply enter your e-mail address below.

Privacy Notice

Unsubscribe here.


Visit our social media hub

Visit our social media hub to see a snapshot of student life and find more USU social media accounts.


Learn more About USU