Symposium: Unsteady aquatic locomotion with respect to eco-design and mechanics

The aquatic environment that animals must operate is in a constant state of change and therefore unsteady by nature. The occurrence of currents, turbulence, tidal oscillations, wave action, and the need for predator and obstacle avoidance, high accelerations and maneuverability make functioning in open water difficult. Turbulence for aquatic animals has importance at scales ranging from micro to macro to global. To meet the challenges of an inherently unsteady environment and unsteady movements, aquatic animals have adapted body morphologies and behaviors that not only act to enhance stabilization, but can also take advantage of the unsteadiness. Mechanics of vortex energy capture, tidal transport, the drag reduction experienced by animals in swarms and schools, stabilization kinematics associated with short-term perturbations, diving strategies, and fast-start behaviors are examples of mechanisms to utilize unsteadiness in an adaptive manner. Furthermore, the unsteady turbulence that animals produce themselves can have ramifications for ocean mixing and global climate change.

Biological and engineering studies of locomotor mechanics and energetically throughout the Twentieth century primarily explored steady-state conditions for self-correcting and stable organisms and vehicles, and contributed many ideas in the understanding of the evolution, behavior and ecology of swimmers and flyers. However, nature is characterized by unsteadiness. In terms of locomotion, organisms are frequently unstable in posture, are not self-correcting when in motion, and experience conditions greatly exacerbated by environmental turbulence (i.e., changing currents, eddies, and vorticity). All these internal and external contributors to a seemingly chaotic status are now being recognized as reflecting fundamental questions such as trades-off between stability and maneuverability, especially in fitness-critical situations (i.e., predator-prey interactions), and energy expenditure and resources for growth and reproduction that consequently impact the evolution of organisms and the habitats they occupy. At the same time, human engineering interests are concerned with creating autonomous vehicles that can operate in equally turbulent settings for which organisms have evolved novel solutions. The rapid growth of interest in unsteadiness in locomotion in the past twenty years has been fueled by new methods, notably in computational fluid mechanics and bio-robotics, resulting in demonstrated impacts of that unsteadiness across taxa, the entire range of organism sizes, and at scales from individual organisms to ecosystems.

The symposium is intended to bring together morphologists, engineers, and mathematicians with an interest in how animals cope with the problem of unsteadiness in the aquatic environment. A major goal is to take theoretical analysis of swimming from the laboratory and examine the interaction of the animal and the environment in the field, where unsteadiness is the general condition.

Sponsors: DCB, DIZ, DVM

Organizers

• Frank Fish, West Chester University, ffish@wcupa.edu
• Paolo Domenici, National Research Council, Italy, paolo.domenici@cnr.it

Speakers

S7.0 Tuesday, Jan. 6, 07:54 FISH, F.:

Introduction

S7.1 Tuesday, Jan. 6, 08:00 FISH, FRANK/E*; HOFFMAN, JESSICA/L:

Stability design and response to waves by batoids

S7.2 Tuesday, Jan. 6, 08:30 COTEL, Aline*; WEBB, Paul:

Living in a turbulent world – Impacts on fish habitat choices and swimming

S7.3 Tuesday, Jan. 6, 09:00 WILLIAMS, T.M.:

The Moveable Feast: A comparison of foraging tactics and energetics in large, stealthy marine and terrestrial carnivores

S7.4 Tuesday, Jan. 6, 10:00 KOEHL, M.A.R.:

Swimming in an Unsteady World

S7.5 Tuesday, Jan. 6, 10:30 KATIJA, Kakani:

Biogenic inputs to ocean mixing: Changes in morphology alter mixing efficiency in medusae

S7.6 Tuesday, Jan. 6, 11:00 MURPHY, D.W.; WEBSTER, D.R.; KANAGAWA, M.; KAWAGUCHI, S.; KING, R.; OSBORN, J.; YEN, J. *:

Aggregative behavior of Antarctic Krill: group interactions, multi-oar biomechanics, and hydrodynamic wake signature.

S7.7 Tuesday, Jan. 6, 11:30 DOMENICI, Paolo:

Unsteady swimming and predator-prey interactions in fish

S7.8 Tuesday, Jan. 6, 13:30 LAUDER, G. V.*; WITT, W. C.; WEN, L.:

Hydrodynamics of Fish c-start Escape Responses Studied with Simple Robotic Models

S7.9 Tuesday, Jan. 6, 14:00 DANIEL, TL*; EBERLE, AL:

Unsteady forces form in flapping foils and depend on fluid-solid coupling in water but not in air.

S7.10 Tuesday, Jan. 6, 14:30 BORAZJANI, Iman:

Unsteady Aquatic Locomotion Simulations: From unsteadiness in straight-line swimming to fast-starts

S7.11 Tuesday, Jan. 6, 15:00 WEBB, P.W.*; WEIHS, D:

Stability and swimming in aquatic vertebrates: evolutionary patterns and possible future directions