Revealing the Hydrodynamics of Fish Schooling: Flow-Mediated Cohesion, Performance Benefits, and Scaling Laws - Keith Moored, Lehigh University
Keith Moored, Associate Professor in the Department of Mechanical Engineering and Mechanics at Lehigh University
Abstract: Fish schools are fascinating examples of self-organization in nature. They serve many purposes from enhanced foraging, and protection against predators to improved socialization and migration. Beyond the implications for biology, engineers can take inspiration from the hydrodynamic benefits of schooling to apply to the design of schools of next-generation bio-robotic vehicles. This new class of schooling unmanned underwater vehicles would enable unprecedented efficiency, maneuverability, agility and stealth; as well as unlock novel missions that require distributed tasks or swarming. However, our understanding of the hydrodynamic interactions in schools is primitive. Importantly, the links from the organization, synchronization, and kinematics of individuals to the performance and stability of a school has yet to established.
In this talk I will present recent work examining the influence of school organization and synchronization on the locomotion performance and stability of simple interacting pitching hydrofoils. Experiments and potential flow simulations will detail the flow interactions that occur between a pair of pitching hydrofoils – a minimal school – with an out-of-phase synchronization. It is discovered that the flow interactions provide cohesion between the foils and, specifically, that there is a two-dimensionally stable equilibrium arrangement that arises. This stable side-by-side arrangement is verified numerically and, for the first time, experimentally for freely-swimming foils undergoing dynamic recoil motions. Significant thrust and efficiency benefits are also determined for various organizations of the minimal school. Focusing in on the side-by-side organization, the origin of the forces that balance to produce an equilibrium arrangement are discovered. New physics-based scaling laws are developed for the hydrofoils’ equilibrium arrangement, thrust generation, and power consumption, which are found to be in good agreement with inviscid simulations and viscous experiments. Going beyond a minimal school, we examine stable arrangements for larger schools of foils by searching for repeating patterns of known stable arrangements. Advances toward examining stable arrangements in real fish schools, and bio-robots alike will be discussed.
About: Dr. Keith Moored is an Associate Professor in the Department of Mechanical Engineering and Mechanics at Lehigh University. He received a B.S. in Aerospace Engineering and a B.A. in Physics at the University of Virginia in 2004, and his Ph.D. in Mechanical and Aerospace Engineering also from the University of Virginia in 2010. From 2010-2013, he was a Postdoctoral Research Associate and Lecturer in Mechanical and Aerospace Engineering at Princeton University. Dr. Moored’s research interests are in bio-inspired propulsion, unsteady aerodynamics and fluid-structure interaction. He is currently leading an ONR MURI topic on the hydrodynamics of schooling and has previously been a PI on another MURI topic on non-traditional propulsion. He has received an NSF CAREER award for examining the fluid dynamic interactions among schooling swimmers.