Meeting Abstract

130.2  Monday, Jan. 7  Hydrodynamics of Self-propelling Flexible Synthetic Shark Skin Membranes WEN, L*; LAUDER, G.V.; WEAVER, J.C.; KOVAC, M; WOOD, R.J.; Harvard University; Harvard University; Harvard University; Harvard University; Harvard University liwen@oeb.harvard.edu

Through the studies of man-made materials, considerable effort has been made to understand how the morphological features of shark skin may reduce static hydrodynamic drag. However, no study has yet quantitatively examined the hydrodynamics of micro-fabricated synthetic shark skin with controllable denticle morphology and mechanical properties, especially under conditions of dynamic deformation. We present the first study of the design, fabrication, and hydrodynamics of a synthetic, flexible shark-skin membrane which is capable of bending like the skin of a swimming shark. The 3-D model of the denticles was based on micro-CT reconstruction of the skin of the shortfin mako (Isurus oxyrinchus). Using 3-D printing, thousands of rigid synthetic shark denticles were placed on flexible membranes in a controlled, non-random pattern. These skin-model membranes were actuated at the leading edge in a heave and/or pitch motion using a robotic device, allowing the undulating membranes to swim at their self-propelled speed. Additionally, digital particle image velocimetry (DPIV) was used to understand how flow modification occurs in the near-surface region and the surrounding area of the undulating membranes. Hydrodynamic results, including self-propelled swimming speed, power consumption and wake flow, were quantitatively compared with those of a smooth membrane without surface denticles. Beyond broadening our understanding of the biomechanics of shark skin, the results of this study may be employed to optimize designs of human swimsuits, gas- transmission lines, and the propulsive performance of biomimetic swimming robot etc.