Leaf resilience to raindrops provides insight into energy harvesting potential

To a leaf, a falling raindrop has the same mass as a bowling ball falling on a person. So how do leaves survive? A new study sheds light on the physical dynamics that help leaves react to the effects of raindrops, with potential applications in agriculture and renewable energy harvesting.

In the paper “Resonance and damping in droplet-cantilever interactions,” published in Physical Review Fluids, the researchers used high-speed photography to capture and analyze the impact of a water droplet hitting a plastic beam, and the beam We are measuring both vibrations. The same goes for the deformation of the drop in response to impact.

Lead author Sunghwan Jung, professor of biological and environmental engineering in the College of Agriculture and Life Sciences, compared the beam to a stepping stone.

After a decline occurs, “the plate goes down and the decline extends up,” he said. “And as the board rises, the descending is pushed down. Because the board moves in the opposite direction, it creates a strong damping effect, resulting in less vibration, which is beneficial for the plant.”

The study also addresses unexplained deviations from the model that other researchers have documented but do not understand. That is, when the beam reaches a certain length, the water droplets become more deformed and move, and the vibrations of the beam decelerate faster.

“This contradiction kept appearing in every graph,” said lead author Crystal Fowler, a doctoral student in bioengineering. “We found that when the natural frequency of the beam matched the natural frequency of the droplet, the droplet motion became even larger.”

Fowler said they found that the more rapidly the drop waves, the higher the damping value and the faster the beam vibrations decrease. For plants, less vibration or faster recovery after a shock can mean less stress and a longer lifespan.

This research could help scientists understand how rain flows through forest canopies or how plant morphology evolves. The research also works in conjunction with other plant-based projects in Jung’s lab to explore how spores are dispersed by rain and how plant vibrations can be used to measure plant hydration. I understand.

Another application is the development and improvement of renewable energy generation technologies. By replacing the beam with a piezoelectric material (a material that generates energy when pressure is applied), it could potentially generate electricity when rain hits it.

“In this material, vibrations create energy,” Jung said. “Imagine a tower with these beams. It looks very natural, but it’s a tower that’s harvesting energy from the rain.”

This paper is the first publication for Fowler, a Navajo Nation citizen who grew up surrounded by plants and gardens. “It’s the point of discovering something new,” she said. “I love discovering things and unleashing my curiosity, and I realized early on that bioengineering offered a way to understand the world.”