Mechanical engineering professor sets new course with NSF ocean expedition

Erin Cassidy Hendrick
September 30, 2019

UNIVERSITY PARK, Pa. — Matthew Rau, assistant professor of mechanical engineering at Penn State, spent 10 days cruising north of Oahu, Hawaii, in the summer of 2019. But it wasn’t for a vacation — Rau was conducting foundational research that could aid the understanding of carbon dioxide absorption within the Pacific Ocean and its potential impact on climate change.

“This experience was really a jump-start into this new research area,” Rau said.

“Engineers have so many skills that can be hugely valuable in environmental fields. We often overlook it, but there are so many opportunities for mechanical engineers to contribute to the world around us.”

— Matthew Rau, assistant professor of mechanical engineering

The trip, organized through the University-National Oceanographic Laboratory System (UNOLS) and funded by the National Science Foundation (NSF), was a critical opportunity for Rau to gain experience with oceanographic field work and set a new course for his research.

“The ocean is full of particulate matter, like clay, sand, microplastics, but it’s mostly organic matter like plankton,” he said. “These particulates often end up clumping together and the bigger they get, the deeper they can settle in the water.”

This has some benefits, mainly that the carbon dioxide naturally absorbed into these particulates also sinks further into the ocean. An effect of this phenomena is carbon sequestration, which is the long-term storage of the gas that can help moderate climate change and ocean acidification.

But the forces of nature are more complicated than they appear. Our current understanding of the physics surrounding this process predicts the particulates will exponentially clump together, becoming ever larger and sinking ever faster.

“But that’s not what’s happening,” Rau said. “So, we are trying to understand the fluid forces and the turbulence of the ocean that causes these particles to break apart.”

Rau previously researched multiphase flows, specifically how bubbles interact with liquids and how fluid flows around them in heat transfer applications.

“A lot of that knowledge in bubbly flows translates over to this area in particulates,” Rau said. “When I found out the potential impact of this knowledge on the global scale through climate models, it further motivated me to pursue it.”

Rau’s new research area of building foundational knowledge to strengthen humanity’s understanding of the ocean is a natural extension of his previous work. 

“This is a small piece of a really big puzzle,” Rau said. “Through this work, if we can make better predictions on how the ocean sequesters carbon, our predictions for carbon dioxide uptake from the atmosphere and its role in our changing climate will be better.”

Rau was one of 18 scientists selected nationwide for the cruise. The group worked together to take measurements and conduct experiments, and Rau is confident the collaborations between the cohort will continue in the future.

“This trip was really to give early career researchers who will be tomorrow’s chief scientists a chance to gain experience organizing and taking measurements on a cruise,” he said.

As a result of this training, Rau is actively submitting NSF proposals to continue gathering the critical field measurements to navigate this new research area. 

“Engineers have so many skills that can be hugely valuable in environmental fields,” Rau said. “We often overlook it, but there are so many opportunities for mechanical engineers to contribute to the world around us.”

  • A group of scientists aboard a ship, holding an NSF flag.

    Rau (second from the top left) and the cohort he worked alongside on the NSF UNOLS cruise.

    IMAGE: Provided

(Media Contacts)

Last Updated October 10, 2019