How Free Swimming Fosters the Locomotion of a Purely Oscillating Fish-like Body

Area of Science:

• Fluid dynamics
• Biomechanics
• Robotics

Background:

• Fish locomotion relies on complex body deformations influenced by water interaction.
• Recoil motions, involving lateral and angular rigid body movements, are crucial for accurate locomotion speed and efficiency calculations.
• Previous studies highlight the importance of the body's rear end in generating deformation, with recent interest in biomimetic applications.

Purpose of the Study:

• To investigate the significant role of recoil motions in fish locomotion.
• To analyze the performance enhancement provided by recoil motions, particularly in damaged fish with impaired tail functionality.
• To apply a theoretical impulse model to free-swimming, oscillating fish to validate the benefits of recoil motions.

Main Methods:

• Utilizing a theoretical impulse model for analyzing free-swimming, oscillating fish.
• Conducting numerical simulations to explore the physical mechanisms behind recoil motions.
• Examining the effects of recoil motions on body deformation and undulation in various conditions, including tail damage.

Main Results:

• Recoil motions dramatically improve swimming performance, especially for fish with damaged or lost tails.
• Body deformation can become oscillating and symmetric in extreme cases, enabling locomotion despite significant damage.
• The study identifies the physical underpinnings of recoil motions, including added mass and vorticity release, through model analysis.

Conclusions:

• Recoil motions are vital for efficient fish locomotion and offer substantial performance benefits, particularly for compromised swimmers.
• The theoretical impulse model provides insights into the physical mechanisms driving these beneficial effects.
• Findings support the application of recoil motion principles in the design of biomimetic robotic fish.