Structural Boundary State Transitions in Turbulent Pipe Flow

L. Moriconi; G. Saisse

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arXiv · 2503.23223

Structural Boundary State Transitions in Turbulent Pipe Flow

L. Moriconi·G. Saisse

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Abstract

Extensive optical measurements of canonical turbulent pipe flows have revealed the existence of structural boundary states (SBSs) -- near-wall low-speed streaks strongly correlated with pairs of counter-rotating quasi-streamwise vortices. In this study, we investigate the number fluctuations of these structures within the framework of statistical mechanics. Specifically, we introduce reduced degrees of freedom to model the low-speed streaks as a dilute lattice gas of hard-core particles. The Metropolis stochastic evolution provides, furthermore, a simple yet effective two-parameter model for describing SBS transitions. The lattice gas approach enables us to derive both the probability of SBS occurrence and the peculiar self-similar correlations that these structures exhibit along the streamwise direction. Our findings give additional support to the idea that the statistically stationary regimes of wall-bounded turbulent flows can be understood as Markov chains of coherent dynamical states in reduced-dimensional phase spaces.

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L. Moriconi, G. Saisse. 2025-03-29. Structural Boundary State Transitions in Turbulent Pipe Flow. https://arxiv.org/abs/2503.23223

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