中国物理B ›› 2025, Vol. 34 ›› Issue (7): 76401-076401.doi: 10.1088/1674-1056/adc669

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Aligning and flocking of ellipsoidal Quincke rollers by flipping

Kai-Xuan He(何凯旋)†, Qi-Ying Ni(倪琦英)†, Xiao-Yi Zhou(周晓怡)†, Wen-De Tian(田文得)‡, Kang Chen(陈康)§, and Tian-Hui Zhang(张天辉)¶   

  1. Center for Soft Condensed Matter Physics and Interdisciplinary Research and School of Physical Science and Technology, Soochow University, Suzhou 215006, China
  • 收稿日期:2025-03-15 修回日期:2025-03-24 接受日期:2025-03-28 出版日期:2025-06-18 发布日期:2025-07-10
  • 通讯作者: Wen-De Tian, Kang Chen, Tian-Hui Zhang E-mail:tianwende@suda.edu.cn;kangchen@suda.edu.cn;zhangtianhui@suda.edu.ecn
  • 基金资助:
    Tian-Hui Zhang acknowledges financial support of the National Natural Science Foundation of China (Grant No. 11974255).

Aligning and flocking of ellipsoidal Quincke rollers by flipping

Kai-Xuan He(何凯旋)†, Qi-Ying Ni(倪琦英)†, Xiao-Yi Zhou(周晓怡)†, Wen-De Tian(田文得)‡, Kang Chen(陈康)§, and Tian-Hui Zhang(张天辉)¶   

  1. Center for Soft Condensed Matter Physics and Interdisciplinary Research and School of Physical Science and Technology, Soochow University, Suzhou 215006, China
  • Received:2025-03-15 Revised:2025-03-24 Accepted:2025-03-28 Online:2025-06-18 Published:2025-07-10
  • Contact: Wen-De Tian, Kang Chen, Tian-Hui Zhang E-mail:tianwende@suda.edu.cn;kangchen@suda.edu.cn;zhangtianhui@suda.edu.ecn
  • Supported by:
    Tian-Hui Zhang acknowledges financial support of the National Natural Science Foundation of China (Grant No. 11974255).

摘要: Active rods propelled along their long axis align their velocities and orientations simultaneously in collision. However, as the propulsion is perpendicular to the long axis, velocity alignment becomes dynamically difficult. Here, we show that ellipsoidal Quincke roller propelled along their short-axis (perpendicular to the long axis) can align their velocities by flipping and form flocking with nematic order. The flipping arises from the reversible transition between the static parallel spinless state and the spinning transversal state of ellipsoidal Quincke rollers. This is possible only near (above) the critical field where both the parallel spinless state and the spinning transversal spinning are metastable. The flipping-facilitated alignment offers an extra aligning mechanism for elongate active agents, and the resulting active liquid crystals serve a model system to explore the defect dynamics as the propulsion deviates from the local nematic orientation which has not been addressed yet.

关键词: Quincke roller, flocking, aligning, flipping

Abstract: Active rods propelled along their long axis align their velocities and orientations simultaneously in collision. However, as the propulsion is perpendicular to the long axis, velocity alignment becomes dynamically difficult. Here, we show that ellipsoidal Quincke roller propelled along their short-axis (perpendicular to the long axis) can align their velocities by flipping and form flocking with nematic order. The flipping arises from the reversible transition between the static parallel spinless state and the spinning transversal state of ellipsoidal Quincke rollers. This is possible only near (above) the critical field where both the parallel spinless state and the spinning transversal spinning are metastable. The flipping-facilitated alignment offers an extra aligning mechanism for elongate active agents, and the resulting active liquid crystals serve a model system to explore the defect dynamics as the propulsion deviates from the local nematic orientation which has not been addressed yet.

Key words: Quincke roller, flocking, aligning, flipping

中图分类号:  (General studies of phase transitions)

  • 64.60.-i
05.65.+b (Self-organized systems) 87.18.Gh (Cell-cell communication; collective behavior of motile cells) 82.70.Dd (Colloids)