Splitting dynamics of coherent structures in a transitional round-pipe flow

Direct numerical modeling of scenarios of the initiation, development, and mutual transitions of coherent turbulent structures in a round pipe at Reynolds numbers 1800 ≤ Re ≤ 4000 is performed. High-accuracy computations were performed for very prolonged time intervals, which made is possible to reveal the fundamental long-lived and statistically stationary flow modes in the transient region between the laminar and established turbulent modes. Reclassification of coherent structures describing the splitting dynamics of the subcritical laminar-turbulent transition is proposed.