Exact Coherent Structures and Phase Space Geometry of Preturbulent 2D Active Nematic Channel Flow

Journal Article · 13 January 2022 · Physical Review Letters

DOI: https://doi.org/10.1103/physrevlett.128.028003 · OSTI ID:1840764

Wagner, Caleb G.  ^[1]; Norton, Michael M.  ^[2]; Park, Jae Sung  ^[3]; Grover, Piyush  ^[3]

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1. Univ. of Nebraska, Lincoln, NE (United States); University of Nebraska-Lincoln
2. Rochester Inst. of Technology, Rochester, NY (United States)
3. Univ. of Nebraska, Lincoln, NE (United States)

Confined active nematics exhibit rich dynamical behavior, including spontaneous flows, periodic defect dynamics, and chaotic “active turbulence.” Here, we study these phenomena using the framework of exact coherent structures, which has been successful in characterizing the routes to high Reynolds number turbulence of passive fluids. Exact coherent structures are stationary, periodic, quasiperiodic, or traveling wave solutions of the hydrodynamic equations that, together with their invariant manifolds, serve as an organizing template of the dynamics. We compute the dominant exact coherent structures and connecting orbits in a preturbulent active nematic channel flow, which enables a fully nonlinear but highly reduced-order description in terms of a directed graph. Using this reduced representation, we compute instantaneous perturbations that switch the system between disparate spatiotemporal states occupying distant regions of the infinite-dimensional phase space. Overall, our results lay the groundwork for a systematic means of understanding and controlling active nematic flows in the moderate- to high-activity regime.

• Research Organization: Univ. of Nebraska, Lincoln, NE (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0022280
• OSTI ID: 1840764
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 2 Vol. 128; ISSN 0031-9007
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English