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Thrust-efficiency limits of a swimming tail with variable chordwise flexural rigidity
Hossam Alqaleiby1, Muhammad R Hajj2
1Davidson Laboratory, Department of Civil, Environmental and Ocean Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA. haboalel@stevens.edu.
Scientific Reports
|February 6, 2025
Summary
This study explores how tail stiffness affects underwater robot performance. Varying stiffness can improve thrust and efficiency, crucial for power-limited bio-inspired robots.
Area of Science:
- Robotics
- Fluid Dynamics
- Bio-inspired Engineering
Background:
- Propeller-driven robots have limitations; bio-inspired designs offer alternatives.
- Flexible tails in thunniform swimming robots can increase thrust but may reduce efficiency.
- Natural swimmers adjust tail stiffness for optimal performance.
Purpose of the Study:
- To assess the impact of varying chordwise tail stiffness on tail deflection and flow dynamics.
- To analyze the contributions of added mass and circulation forces to thrust generation and efficiency.
- To identify flow dynamics and tail deflections that enhance thrust and/or efficiency.
Main Methods:
- Computational fluid dynamics (CFD) simulations were used to model tail kinematics and hydrodynamics.
- The study analyzed tail deflection, flow patterns, and forces (added mass, circulation) under varying stiffness conditions.
- Performance was evaluated based on thrust generation and propulsive efficiency.
Main Results:
- Specific tail stiffness values were identified that enhance both thrust generation and propulsive efficiency.
- The study quantified the contributions of added mass and circulation forces to overall thrust.
- A performance limit was defined, relating maximum efficiency to the thrust coefficient.
Conclusions:
- Varying tail stiffness is a viable strategy for optimizing the performance of bio-inspired underwater robots.
- Understanding the interplay between tail flexibility, flow dynamics, and forces is key to designing efficient robotic swimmers.
- This research provides a framework for defining performance limits in bio-inspired propulsion systems.
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