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Propulsion performance of a skeleton-strengthened fin
1Department of Structural Engineering, University of California, San Diego, La Jolla, CA 92093, USA. qizhu@ucsd.edu
The Journal of Experimental Biology
|June 17, 2008
Summary
Reinforced fish fins with flexible rays enhance propulsion and force generation. Asymmetric fin designs further reduce drag and enable vertical maneuvers, mimicking natural fish swimming.
Area of Science:
- Biomechanics
- Fluid Dynamics
- Robotics
Background:
- Fish caudal fins provide propulsion through complex fluid-structure interactions.
- Understanding fin mechanics is crucial for developing bio-inspired underwater vehicles.
Purpose of the Study:
- To numerically investigate the fluid-structure interaction of ray-reinforced fins.
- To analyze the impact of fin deformability and symmetry on propulsion performance.
Main Methods:
- Simulating a thin foil with nonlinear Euler-Bernoulli beams representing fish fin rays.
- Employing a boundary-element hydrodynamic model for coupled fluid-structure interaction.
- Implementing both homocercal (symmetric) and heterocercal (asymmetric) fin kinematics.
Main Results:
- Anisotropic deformability of ray-reinforced fins significantly boosts force generation.
- Propulsion efficiency increases, while transverse forces and kinematic sensitivity decrease in the homocercal mode.
- The heterocercal mode further reduces transverse force and generates a lifting force for vertical maneuvers.
- Observed wake structures, including vortex rings, align with experimental data from live fish.
Conclusions:
- Ray-reinforced fins offer enhanced propulsion and maneuverability through controlled deformability.
- Asymmetric fin designs are effective for drag reduction and vertical control.
- Numerical simulations provide accurate predictions of fish fin performance and wake dynamics.
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