Saddle-node bifurcation during relaminarization of turbulent puffs in pipe flow
Phys. Rev. Fluids 11, 053902 – Published 22 May, 2026
DOI: https://doi.org/10.1103/n7n8-91m8
Abstract
Turbulent puffs in pipe flow remain sustained for an extended period of time before abruptly transitioning to laminar flow through viscous exponential decay. During the statistically stable state, the topology of sectional streamlines reveals the presence of numerous saddle and nodal points in proximity to the wall. The number of saddle and node points decreases as relaminarization begins, and they migrate away from the near-wall region. In the final stage of relaminarization, direct numerical simulations reveal, in some cases, sequences of saddle-node bifurcations that ultimately lead to the annihilation of saddle-node pairs. The Riccati equation is proposed as a simple approach to model the motion of these pairs.
