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Dynamics of a squid-inspired swimmer in free swimming
1Department of Structural Engineering, University of California, San Diego, La Jolla, CA 92093, United States of America.
Abstract:
The untethered swimming performance of a two-dimensional squid-inspired swimmer is studied. Our model includes fully-coupled fluid-structure interaction and an idealized activation algorithm that drives periodic shape change of the body. We present results of both escape jetting via a single deflation-coasting motion and long-distance swimming via repeated inflation-deflation cycles. In both cases added-mass-related force is found to contribute significantly to thrust generation. Moreover, we find that the increase of the jet speed and oscillation frequency leads to higher swimming velocity. This, however, is achieved at the cost of reduced propulsion efficiency (i.e. higher cost of transport). During long-distance swimming, the system experiences three successive stages, acceleration, steady-state swimming, and off-track swimming caused by symmetry-breaking instability in the wake. Associated with these stages, three wake patterns are observed, nozzle-vortex-dominated wake, transit wake, and asymmetrical wake.
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