Controlling chaos: Periodic defect braiding in active nematics confined to a cardioid

• DOI: 10.48550/arxiv.2401.04363
• Publication Date: 2024-01-01
• Authors: Fereshteh L. Mema...; Derek Hammar; Md Mainul Hasan S...; Mark Elias; Kevin Mitchell; Linda S. Hirst
• Keywords: Topological Entropy; Annihilation; Braid theory

This work examines self-mixing in active nematics, a class of fluids which mobile topological defects drive chaotic flows system comprised biological filaments and molecular motors. We present experiments that demonstrate how geometrical confinement can influence the braiding dynamics defects. Notably, we show cardioid-shaped wells leads to realization golden braid, maximally efficient mixing state exactly three with no defect creation or annihilation. characterize braid using different measures entropy Lyapunov exponent. In particular, measured from stretching rate material lines agrees well an analytical computation theory. Increasing size confining cardioid produces transition fully turbulent state.