Bio-inspired efficient pulsatile locomotion

George Washington University, Washington DC

Investigators

Abstract

PI: Leftwich, Megan Proposal Number: 1604876 The focus of this proposal is to determine the mechanism for high-performance swimming that is used by sea animals that move their flippers in a periodic manner. It is proposed to take real life experimental data for the motion of sea lions at the Smithsonian National Zoological park (SNZ) in Washington, DC, and to mathematically describe the maneuvering motion of these swimmers in order to design robotic prototypes. These prototypes will then be used in a laboratory setting to take detailed measurements of the flow around them. Findings from this research could lead to energy savings because of flow control around submerged objects (e.g., ships, submarines, unmanned robotic vehicles). To understand the hydrodynamics around a large animal, one must first characterize its kinematics. Previous efforts to do so, which inform this work, do not include quantitative descriptions of the relevant parameters for a detailed, controlled hydrodynamic study. At this time, it is proposed to conduct a comprehensive field study at the SNZ in Washington, DC. This study will provide a digital catalog of sea lion maneuvers and a detailed mathematical description of them. The study will initially focus on steady swimming behavior (the "clap") before progressing to include turning, accelerating and other advanced maneuvers. Both two- and three-dimensional data will be obtained using three synchronized digital cameras. This required significant development of markerless three-dimensional tracking techniques for large free-swimming bodies. While methods exist for small-scale motion (insects) or highly predictable motions (human walking), these tools are not available for general locomotion with an unknown trajectory. Once the kinematic data are in place, a replicate will be crated that will be a hydrodynamically quiet unsteady propulsor in a laboratory setting. While observational data of swimming sea lions offer insight into such propulsion, it is not sufficient to understand its hydrodynamic effects on the surroundings. The work proposed here will lay the foundation for the design and construction of a robotic sea lion fore flipper. Finally, high-magnification images of the propulsive surface will allow the investigation of its natural flow control abilities. Educational initiatives involve graduate, undergraduate and high school students. In addition, through the Friends of the National Zoo (FONZ) program, the PI will participate in educational programs at the SNZ including lectures and the creation of educational displays and interactive modules within the California sea lion exhibit. Finally, recent and ongoing media interest in this work provides a platform for dialogs about fluid dynamics with the general public.