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arXiv · 2507.04890

Emergence of Local Ordering and Mesoscale Giant Number Fluctuations in Active Turbulence

Kirti Kashyap·Kolluru Venkata Kiran·Anupam Gupta
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Abstract

We study spatiotemporal chaos in two-dimensional dense active suspensions using a generalized hydrodynamic model. Increasing activity induces a structural transition marked by the formation of intense vortices and giant number fluctuations at the mesoscale. The flow self-organizes into locally polar-ordered regions coexisting with chaotic domains, producing a bimodal velocity distribution and enhanced correlations. This mixed-state morphology underlies the universal statistical behavior observed beyond a critical activity threshold. Reducing the instability timescale yields similar transitions, showing that both activity and instability act as control parameters for pattern formation. An energy-based order parameter derived from the system's budget quantifies and unifies these structural transitions across the phase space of activity and instability timescales.

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Kirti Kashyap, Kolluru Venkata Kiran, Anupam Gupta. 2025-07-07. Emergence of Local Ordering and Mesoscale Giant Number Fluctuations in Active Turbulence. https://doi.org/10.1103/ylbh-8v74

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