Thrust generation and propulsive efficiency in dolphin-like swimming propulsion.

Area of Science:

• Fluid dynamics
• Biomechanics
• Robotics

Background:

• Growing interest in emulating dolphin morphology and kinematics for high-performance underwater vehicles.
• Understanding the hydrodynamic principles of dolphin propulsion is key to biomimetic design.

Purpose of the Study:

• To investigate the hydrodynamics of dolphin-like oscillatory kinematics in forward propulsion.
• To analyze the impact of body oscillation and fluke motion on thrust generation and drag reduction.
• To determine the role of peduncle and fluke flexion in optimizing swimming performance.

Main Methods:

• Utilized a computational fluid dynamics (CFD) method.
• Created a realistic three-dimensional surface model of a dolphin.
• Reconstructed dolphin swimming kinematics from video recordings.

Main Results:

• Dolphin oscillation enhances boundary layer attachment, reducing body drag.
• Fluke flapping generates significant thrust during both downstroke and upstroke via vortex ring shedding.
• Downstroke jets are stronger than upstroke jets, resulting in net positive lift.
• Varying peduncle and fluke flexion angles significantly impacted performance.

Conclusions:

• Dolphin-like swimming kinematics, particularly peduncle and fluke flexion, are crucial for efficient propulsion.
• Optimal thrust and propulsive efficiency are achieved with slight decreases in peduncle flexion and slight increases in fluke flexion.
• Findings provide valuable insights for designing advanced biomimetic underwater vehicles.