technique to manipulate water waves to precisely control floating objects

 A team of international scientists co-led by Nanyang Technological University, Singapore (NTU Singapore) have discovered a way to manipulate water waves, allowing them to trap and precisely move floating objects -- almost as if an invisible force were guiding them.

The method involves generating and merging water waves to create complex surface patterns, such as twisting loops and swirling vortices.

Laboratory experiments showed that these patterns can pull in nearby floating objects, like small foam balls the size of rice grains, and trap them within the patterns.Some patterns act like tweezers or a "tractor beam" to hold the floating balls in place on the water's surface so they do not drift away. Others cause the balls to spin about on their centres and move precisely along a circular or spiral path within the patterns.

Unlike ordinary ripples, these wave patterns remain stable even when disturbed by minor external waves

This technique uses real-world physics to control and shape water waves, but the effect resembles that of an unseen force moving things, as fictionalised in popular shows and books.

The breakthrough, published in the scientific journal Nature on 5 February 2025, opens the possibility of using water waves in new ways.

For example, the technique could be developed further to corral spilt liquids and chemicals that float on water to make them easier to clean up.

The method could also be scaled up to guide larger floating objects, and possibly vessels, along a desired path on the water, even if they do not have working engines.

"Our findings are the first step in exploring how water waves can be shaped to move objects, with many potential applications in the future," said Assistant Professor Shen Yijie, one of the co-leads of the research from NTU Singapore's School of Physical and Mathematical Sciences, and School of Electrical and Electronic Engineering.

"We've shown that water waves can be used to precisely move floating objects as small as rice grains. Future research could study even smaller waves such as those on the scale of cells that are hundreds of times smaller, as well as much larger sea waves that are a thousand times bigger," he added.

Lessons from light

The technique to shape water waves was developed through an interdisciplinary effort inspired by Asst Prof Shen's prior work -- using light waves to create complex structures or patterns of light.

Source: ScienceDaily