Projects in biomechanics of locomotion
Pressure and forces produced by free-swimming fish and jellyfish
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Marine animals have amazing swimming abilities, which they constantly use to find food, avoid predators, migrate, or locate mates. And so, understanding swimming locomotion can help us understand some of the factors driving the evolution marine animals we see today. But, measuring the forces acting on a freely-swimming animal turns out to be incredibly difficult. In collaboration with John Dabiri at Stanford University, I have developed a new method for estimating the swimming forces produced by different parts of an animal's body. Using this and other visualization techniques, I am able to measure these swimming forces non-invasively and describe the underlying physics that the animal uses to create them.
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Modeling non-uniformly flexible propulsors
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Fish are remarkable swimmers, able to move quickly, with agility, and efficiently. Unlike man-made systems which typically feature rigid structures, the fish's body is notable for its flexibility. Moreover, the fish's body in not uniformly flexible - it is stiff near the head, and much more flexible near the tail. The majority of previous models of fish locomotion have used uniformly flexible designs under unrealistic swimming conditions. I used a flapping-hydrofoil system to investigate how various distributions of stiffness contribute to swimming performance. Models with non-uniform distributions nearly always outperformed their uniform counterparts.
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Bending patterns in swimming and flying animals
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Swimming and flying animals oscillate their flexible bodies and appendages to create the forces they need for locomotion. Over time, these structures have evolved toward designs which allow these animals to move effectively. Yet, the addition of flexibility to models of animal locomotion has led to mixed results - sometimes it helps, but other times, it hinders - and no clear criteria for effective locomotion have emerged. By investigating how the propulsive structures of animals bend, we were able to describe a highly predictable pattern of bending in fish, birds, bats, mollusks, whales, and insects. This information will inform future investigations into how animals move, as well as the design of new underwater vehicles.
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