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Stability of a Dumbbell Micro-Swimmer
1Department Finemechanics, Graduate School of Engineering, Tohoku University, Miyagi Prefecture 980-8579, Japan. ishikawa@bfsl.mech.tohoku.ac.jp.
Micromachines
|January 10, 2019
Summary
Researchers studied dumbbell squirmers, finding stable forward swimming requires external torque. Stable side-by-side swimming is achievable for puller types, and fore-and-aft configurations enhance speed when the rear squirmer is a strong pusher.
Area of Science:
- Fluid dynamics
- Microhydrodynamics
- Biophysics
Background:
- The squirmer model analyzes micro-swimmer propulsion via surface velocities.
- Applications include microorganisms and Janus particles.
- Dumbbell squirmer dynamics are not well understood, hindering micro-machine assembly.
Purpose of the Study:
- Investigate the swimming behavior and stability of dumbbell squirmers.
- Determine conditions for stable locomotion in connected micro-swimmers.
- Explore potential for engineered micro-swimmer assemblies.
Main Methods:
- Linear stability analysis for far-field behavior.
- Boundary element method (BEM) for swimming speed calculations.
- Analysis of dumbbell squirmers connected by rigid rods and springs.
Main Results:
- Dumbbell squirmers lack inherent stable forward propulsion in the far-field without external torque.
- Stable side-by-side swimming configurations were identified for 'puller' type squirmers.
- Fore-and-aft configurations with a strong 'pusher' at the rear demonstrated stable swimming and increased speed.
Conclusions:
- Dumbbell squirmer stability is configuration-dependent.
- Specific configurations (side-by-side pullers, fore-and-aft pushers) enable stable locomotion.
- Findings inform the design of assembled micro-swimmers for future applications.
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