Meeting Abstract

81.4  Sunday, Jan. 6  Hydrodynamic gait identification in squid using volumetric flow imaging BARTOL, I.K.*; KRUEGER, P.S.; THOMPSON, J.T.; Old Dominion University, Norfolk, VA; Southern Methodist University, Dallas, TX; Franklin and Marshall College, Lancaster, PA ibartol@odu.edu

Squids employ two fundamentally distinct mechanisms of propulsion, pulsed jetting and fin oscillations. Simultaneously quantifying complex wake vortex flows from these two systems and identifying coordinated gaits with speed related propulsive performance benefits is a significant challenge, requiring new technologies and approaches. With the goal of identifying coordinated hydrodynamic gaits, flows around brief squid Lolliguncula brevis swimming against a current in a water tunnel were visualized and quantified using a volumetric (3D) approach, known as defocusing digital particle tracking velocimetry (DDPTV). The 3D flows generated by the jet and fins were complex, with multiple vortex wake patterns being detected for both the jet and fins, ranging from isolated to interconnected vortex structures. To help identify distinct wake patterns, quantitative tools, including proper orthogonal decomposition (POD) and topological techniques using critical point properties, were used to analyze the wake measurements, and propulsive performance metrics were calculated. While significant variability was observed, especially for fin flows, several distinct wake patterns were identified, suggesting that our approach has potential for (a) assigning quantitatively meaningful metrics to qualitatively observable differences in wake features and (b) identifying true hydrodynamic gaits in swimmers with multiple propulsive systems. Funded by NSF grant IOS-1115110.