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Undulatory Propulsion at Milliscale on Water Surface
Ziyu Ren1,2, Kagan Ucak2, Yingbo Yan2,3
1School of Mechanical Engineering and Automation, Beihang University, Beijing, 100191, China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|March 14, 2024
Summary
Millimeter-scale flexible sheets use oscillatory pitch motion for undulatory locomotion on water. Optimizing parameters like stiffness is key for efficient swimming and designing future soft robots.
Area of Science:
- Fluid Dynamics
- Robotics
- Soft Matter Physics
Background:
- Oscillatory pitch motion at the leading edge of flexible sheets can generate undulatory locomotion on water surfaces.
- This swimming strategy is analogous to biological propulsion, like a honeybee's wing vibrations.
- The influence of various parameters on this swimming strategy is not well understood.
Purpose of the Study:
- To investigate the propulsion mechanics of millimeter-scale flexible sheets on water.
- To explore the impact of different parameters on undulatory locomotion.
- To understand the underlying physical principles driving this swimming strategy.
Main Methods:
- Utilized magnetic milliswimmers to experimentally probe propulsion mechanics.
- Systematically varied parameters such as actuation frequency, pitch amplitude, bending stiffness, and hydrofoil length.
- Analyzed the resulting body waveforms, propulsion speeds, and energy efficiency.
Main Results:
- Undulatory propulsion is driven by capillary forces, added mass effects, and radiation stress from capillary waves.
- Altering parameters modifies the body waveform, significantly affecting propulsion speed and energy efficiency.
- Optimizing body stiffness is crucial for efficient swimming, balancing speed and energy consumption.
Conclusions:
- The study elucidates the physics of undulatory water surface propulsion.
- Findings provide insights into optimizing the design of small-scale swimming soft robots.
- Induced water flow is confined to the surface and evolves with varying parameters.
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