Flow features in the wake of freely flying European Starling, Western Sandpiper and American Robin

Event Location: 
BCCMWS 100
Event Date: 
Thursday, February 5, 2015 - 3:00pm
Event Type: 
SCMSS Seminar Series

Presenter:Roi Gurka
Associate Professor in the School of Coastal and Marine Systems Science (CCU)

Abstract

The high performance capabilities of flapping wings, especially in low Reynolds number configurations where static wing performance typically suffers, has been a focus of much research. This topic has been studied extensively for the last 100 years using observations of birds’ flight, laboratory studies as well as numerical simulations. Yet, the fundamental question remains open. How do birds fly efficiently, and what are the mechanisms that they use in order to travel long distances with low energy costs? Birds affect their wake by controlling the turbulence in such a way that reduces drag and enhances lift.

The interaction between turbulence and bird flight is presented using three types of birds: European Starling, Western Sandpiper, and American Robin. The near wake of freely flying birds was measured using high speed, time-resolved, particle image velocimetry (PIV), simultaneously with imaging the wing kinematics, using high-speed cameras. The system samples the flow field continuously for 20 minutes, which enables us to capture the wake evolution over multiple flap cycles. Time series of the vorticity fields have been expressed as composite wake plots, which depict segments of the wing beat cycle for various span-wise locations in the wake. The composite wake plots reveal various characteristics of the wake during the upstroke (US) and downstroke (DS) phase of the flapping as well as the transition between the US to DS and vice versa. Comparison between the near wake fields behind the three birds reveals remarkable similarity in their wake structure.

Speaker Information

Roi Gurka obtained his Bachelors, Masters, and Ph.D. in Mechanical Engineering at the Technion University in Haifa, Israel with specialization in fluid dynamics and turbulence. He completed a post-doc at The Johns Hopkins University in Baltimore Maryland, where he examined wave-current-turbulence interactions in the bottom boundary layer of the coastal ocean. He has held faculty positions at the University of Western Ontario in London Canada as well as at the The Ben-Gurion University in Beer-Sheva Israel, and is currently an Associate Professor in the School of Coastal and Marine Systems Science at Coastal Carolina University. His research interests include avian aerodynamics, insect odor-based navigation, stratified flows, scalar transport, and fluid-structure interaction. He is also involved with the research and development of novel fluid measurement technologies.