Bubble PIV technique to measure the velocity field of a free-swimming California sea lion


  • Megan Clare Leftwich George Washington University, United States of America
  • Gino Perrotta George Washington University, United States of America
  • Frank E Fish West Chester University, United States of America




marine mammal, velocity fields, Bubble PIV, thrust production


Fish et al. (2014) adapted laboratory PIV for safe use on larger animals. As opposed to seeding the entire flow with reflective particles and illuminating a plane of the flow with a laser, they produced a sheet of small bubbles and used sunlight for global illumination. Underwater cameras imaged the flow in a method similar to traditional PIV. This technique was used to measure the flow around a swimming dolphin and estimate the thrust produced during a tail stand maneuver (Fish et al. (2014, 2018)). In the current work, we will extend the modification of PIV of Fish et al. to measure the flow produced by a swimming sea lion also using bubbles as seeding particles and sunlight as illumination. This is the first time that the flowfield of a swimming sea lion has been directly measured. We will present an extensive extension to the image processing required to measure flow under field conditions. Finally, we will present the flow generated by propulsive strokes of an adult female (Cali) sea lion freely swimming through a pool of stationary water.

Author Biography

Megan Clare Leftwich, George Washington University, United States of America

Dr. Megan C. Leftwich is an Associate Professor in the Department of Mechanical and Aerospace Engineering at The George Washington University. She holds a Ph.D. and M.A. in Mechanical and Aerospace Engineering from Princeton University and a B.S.E. degree from Duke University. Prior to joining GW, she was the Agnew National Security Postdoctoral Fellow at Los Alamos National Lab from 2010 to 2012. Her current research interests include the fluid dynamics of rotating airfoils, high performance jetting for aquatic locomotion, unsteady activation for undulatory propulsion, and the fluid dynamics of human birth. Prof. Leftwich has a deep interest in diversity in technical fields and STEM education from the first year through the Ph.D. Professor Leftwich is an Office of Naval Research 2017 Young Investigator Award Recipient. Additionally, she is the winner of the 2018 SEAS Dean’s Faculty Recognition Award, the 2017 SEAS Outstanding Young Researcher Award and the 2016 SEAS Outstanding Young Teacher Award. In 2015 she won a STEM Academy Teaching Innovation Grant to create MOOC videos for a non-MOOC class. Professor Leftwich received an ONR Summer Research Faculty Fellowship in both 2015 and 2016. In 2014, she received the Young Researcher Award at the 4th International Conference on Experimental Fluid Mechanics in Beijing, China. Her work on unsteady propulsion has been profiled in over 20 popular media venues including: Wired, the Smithsonian Magazine and the New York Times.






Biological Flows