If you’ve ever been to an aquarium, you’ve likely lost yourself staring into a sea of blue at an array of varied and exotic underwater creatures.
You observe their colors and marvel at the way each species interacts with others, but have you ever paused to consider the unique ways these animals move through the water?
Keith Moored certainly has. “I once attended a fluid mechanics conference that took place at the Long Beach Aquarium in California,” he says. “Everyone in bio-propulsion, including myself, invariably end up lost in thought, staring at the fish.”
Moored, an assistant professor of mechanical engineering and mechanics, studies bio-propulsion—movement by legs, fins, wings, and other muscles instead of mechanical means—since his time as a student at the University of Virginia. It’s also the focus of the prestigious CAREER Award he recently received from the National Science Foundation.
Ultimately his work could answer the question: What can scientists borrow from nature to achieve teams of aquatic vehicles as optimized for underwater movement as fish swimming in a school? Gaining a comprehensive understanding of these collective interactions could help scientists determine how fragile biological networks are to overfishing, loss of habitat and a changing climate. It could also open the door to the development of schools of bio-inspired technologies.
A deep dive into biomechanics
“As an undergraduate, I studied aerospace engineering and physics,” he says. “As my Ph.D. work began, I started on a project to develop a bio-robotic device that would swim like a manta ray.”
The manta’s large, morphing fins are designed to enable swift and efficient movement, characteristics his research adviser wanted to explore as a way to improve aircraft wings. The project, which was funded by the U.S. Department of Defense as a Multidisciplinary University Research Initiative (MURI), allowed Moored to apply both his knowledge of mechanics and his love of marine life to a project with wide-reaching military and civilian application.
This work also led to other projects he would join as a faculty member at Lehigh with the goal of improving underwater robots so that they look, sound, and move exactly like fish.
“When we design aircraft, we know how much lift should be generated and how much drag is being produced, but underwater it is a totally different world,” Moored says. “Design equations for efficient bio-robotics simply didn’t exist—how could we unlock the basic science so that engineers could build more reliable robots? Developing those equations was our job. I have always loved the water and aquatic animals, so this felt like the perfect way to connect my passions and make an impact—putting their secrets to work for us.”
Among other civilian and military applications for this work, Moored says, is a need to better observe and track fish without disrupting their habitat.
“From a biological perspective, learning more about underwater species is challenging because current technology tends to scare away a lot of fish,” he says. “And often, in terms of speed or the amount of energy the robots can carry with them, our machines just can't keep up with them.”
Quantifying strength in numbers
For his CAREER project, Moored is continuing to study bio-propulsion in fish, but he’s applying it to the way they move collectively. His project focuses on extending our knowledge of the fluid dynamic interactions that occur in animal collectives: flocks, schools and swarms. The overarching research goal of the program is to understand the flow mechanisms that occur among unsteady, three-dimensional interacting bodies in complex arrangements. This will help scientists determine the sensitivity of biological networks in relation to overfishing, loss of habitat and the climate change.
"The key to making a breakthrough in the design of high-performance collectives of bio-inspired devices is to understand the fundamental fluid mechanics of collective interactions," Moored explains. "But right now we don't have a thorough understanding of the fluid dynamics among schools of fish."
Moored says dynamic interactions occur between multiple fish that change the mechanism by which each individual swims as fast and efficiently as possible. “In previous research, we’ve found that the fluid dynamics between fish in groups creates forces between them. These fluid-mediated forces cause fish to arrange themselves naturally, kind of like atoms in a lattice-like structure,” he says. “If they break position, the forces pull them back.”
He hopes the project will lead to further advancements in underwater biotech, including the development of schools of bio-inspired robots that can perform more complex tasks than single swimmers.
But underwater life is only part of Moored’s research focus. He also has an eye toward the sky, as he works on several projects in the Unsteady Aerodynamics Laboratory in Packard Lab with aerodynamic applications.
One project is funded through the U.S. Army Armament Research, Development and Engineering Center. “I’m working on this with Terry Hart, a retired astronaut and a fellow faculty member in our mechanical engineering department,” Moored says. “We’re developing a gun-launchable unmanned aerial vehicle (UAV) that can survey the area around buildings or over hills on the battlefield.”
Moored has a device that flies right now, but he and the team have more work to do in order to improve performance—“to make the UAV fly higher, faster, and for longer,” he says.
This dual interest in both sides of his field started at an early age. Moored remembers his grandfather asking him as a young boy what he wanted to be when he grew up.
“I told him I wanted to be a scuba diver, but he told me that wasn’t a career, so then I said I’d be an astronaut,” he says.
In college, he says he realized he could blend those two things, and it all came together for him under the water. “As a grad student, I got to dive in Micronesia with some of my research colleagues and swim with the rays we were studying,” he says. “We learned a lot about them, and even though it was a professional endeavor, it was a ton of fun. Now, I feel pretty lucky to be able to say this kind of thing is ‘all in a day’s work.’
And what about his astronaut side?
“Maybe if they find some manta rays up there,” he jokes.
