Utilizing passive elements to break time reversibility at low Reynolds number: a swimmer with one activated element

Area of Science:

• Fluid dynamics
• Biophysics
• Robotics

Background:

• Microscopic swimmers must break time-reversibility for motility, as per the scallop theorem.
• Biological and artificial systems operate at low Reynolds numbers where viscous forces dominate.

Purpose of the Study:

• To propose a novel, versatile swimmer design for low Reynolds number environments.
• To demonstrate a new kinematic scheme for breaking time-reversibility and achieving net motion.
• To analyze the maneuverability and steering capabilities of the proposed swimmer.

Main Methods:

• Two-dimensional simulation of a novel swimmer system.
• Analysis of swimmer motion under varying operating parameters.
• Identification of minimal parameters for effective steering.

Main Results:

• The proposed swimmer effectively breaks time-reversibility to generate motion.
• The system exhibits maneuverability, with steering capabilities identified.
• Limits and minimal operating parameters for the swimmer were determined.

Conclusions:

• The novel swimmer design offers a versatile mechanism for propulsion at low Reynolds numbers.
• This model system can inform the design of both biological microswimmers and artificial micro-robots.
• The study provides insights into kinematic strategies for achieving directed motion in viscous fluids.